Not terribly soon, I'm afraid, since there's not a lot of work being done on the mod (due to the vast majority of the Tianxia devs not being active at all) and there's a lot of work that needs to be done.
The best-case scenario for the map rework is that all provinces are on the map (in a non-polished form) about a month from now (the actual working time is significantly less than a month, but I don't have all the time in the world to spend working on Tianxia and don't have the energy to spend all of my free time working on Tianxia). At that point, many/all (depending on what's getting done while I'm adding provinces; I'm focusing on that and have told people to work on the rest in the meantime) of the provinces will not have proper positions for graphical stuff (meaning units, councillors, etc. won't show up properly), will not have the proper amount of baronies (seven per province, due to Prosperity requiring that), will be missing proper CoAs (everything currently uses a placeholder CoA since it would take me longer to check every CoA than to copy and rename the placeholder for each title, and we had some placeholders even before the work on HF began), will be missing a proper (and ideally complete, at least as far as the top liege goes) title history (which depends on the character history) file (meaning you can't start as someone holding the province and that the province will be fully independent when the game starts), might have a bad province history file (the culture/religion/starting holdings might be weird), or might have other issues (e.g. missing/bad localization, a weird shape, a lack of adjacencies (strait/major river crossings), no starting tech values, not being in all relevant geographical regions, not having proper Black Death patterns, and/or not being a Silk Road (and Silk Road trading post, where relevant) province), some of which must be fixed before we even are prepared to share the mod with the Closed Alpha testers.
Beyond the above (a bunch of which isn't stuff that's possible to just port from the 2.8 version), there's a bunch of things that must completed/added before the mod works with HF (e.g. rel head titles and localization for our new Doctrines), a bunch of things that should be added (as part of HF compatibility/earlier compatibility) that doesn't prevent the mod from being playable but that is noticeable in its absence (Warrior Lodges for all of our pagans, holy orders for various religions, unique retinues/cultural buildings for everyone, more artefacts for everyone (especially basic smith-crafted ones), and basic flavour (e.g. a feast-like decision/event chain for all religions)), a bunch of things that should be added that's new content (which I'm not going to discuss here), some old stuff (that's currently commented out internally due to varying issues) that should be either fixed or fully removed (and other stuff that might need to be tweaked due to e.g. assuming that the recipient (and possibly the sender) automatically is an adult male character in whatever part of the world a culture/religion historically would be present it), a bunch of localization that should be checked (for grammar/spelling mistakes, proper pronouns (since some of it likely predates the SoW laws and thus assumes that various rulers are male), and just plain bad writing), and various other things that we might want to add that may or may not be worth delaying a release (public or Closed Alpha only) for and that may or may not be easy to add (and sometimes we have a lot of individually easy things to add that makes it a fairly big undertaking to add it all).
All of the above might not need to be done for the mod to be as playable as the internal 2.8 version (which only the Closed Alpha testers got to see, since a decision was made to not update the public version) is/was (though some bits, such as the map, are strictly necessary to get done before we're at that point) and to have basic HF compatibility, but even when the mod gets to that point it might not immediately be shared in a public fashion (since a decision was made to not do so in the past). We've got a list of goals (that might grow or shrink, and that I'm not going to share here) that we want to complete before we move on to the (Closed) Beta, and some of those goals are rather big, so there might be further delays due to that (and possibly also due to further DLCs/vanilla patches forcing us to do more compatibility work; even though HF wasn't as related to our stuff as JD, it still messed with a bunch of files that we also had tweaked and added some new things we need/needed to add).
Understandably, this isn't want you wanted to hear, and understandably this is rather vague, but there are things that I cannot (or should not) say here, a lot of uncertainties about how quickly things can get done due to not knowing how many devs will be even somewhat active (judging by recent and not-so-recent activity in our internal forum and elsewhere, not many, even if I'm generous with how I define "being active"), not being sure how difficult some things might be to do (some things are simple on paper, but turn out to be rather more difficult to actually do), and not being fully certain if our goals will change, and a number of things that I've got no control over (for example, I don't get to decide when we release something). I'll just say that I'm doing all the work I reasonably can do to ensure that a new version can be released as quickly as possible, but that releasing something quickly might not be possible.
