This still seems pretty slow. What exactly is slowing you down? AE? Coring? You should be using vassals to keep down OE and take more warscore with reconquest claims. You should at least be into East Africa by now, have your 3 TCs for the age bonus, and probably have a bigger chunk of India (although... that might be different from my 1.22 progress below if India has more time to get consolidate....).
Your ideas are fine, but I'm not sure I would've picked Aristo (I'd fill with infl/explo/quantity instead) and I'd chose influence before diplomatic most of the time.
Also, why are you culture converting? And why are you improving relations with someone you're spying on and already have -156?
Here's a progress shot of my first WC attempt @ 1599 (soon to be completed successfully), for comparison. I had 4708 dev, twice yours. I was also Ottos, but went Coptic. This is from 1.22, but by that point I think the difference between the starts should be small. Afghanistan (not an optimal pick, but they didn't fill out their ICC ambition, so it turned out ok) and Marehan are vassals (using a release-and-reconquest strategy). Spain (who integrated Naples) and Aragon are under PUs.
Collecting everywhere early and mid-game may be marginally more profitable (and certainly is easier to administer), but once you have sufficient trade power (i.e., monopolies or near monopolies) everywhere it is more profitable to steer.
Collecting vs. steering is highly variable and I think it has a lot to do with exactly
how people expand. I know
@bly08 has plenty of examples of when collecting everywhere is the right move, but I think that has a lot to do with his (mindblowingly-impressive) style and pace. To expand that fast, you have to focus on continually opening up new fronts and probably have a decent amount of TP everywhere, but you still might not have finished off all the little nations nipping away at your wealth/power. Collecting everywhere (high value with high TP) is the best in this case because any steerage will cause significant loss of income.
In contrast, when I blob, I find I try to balance opening up new fronts and consolidating TP (also containment and taking forts, but that's outside the scope of trade) when deciding who to war/which provinces to take. This tends to leave me with pretty strong trade networks (chains of 90% -100% control) which allow some steering along the way to prevent trade from leaking & gain the steering bonus. Depending on how many merchants I have, I find the best option is some mix of steering (especially when you can "steal" TP when transferring countries don't have merchants) and collecting at key nodes (usually where I have high TP that prevents trade from leaving the network).
I think the best advice is that trade is highly variable and quite dynamic, so you really just have to try a couple different options.