I am not so sure. It's going to be hard, but not impossible. I was initially planning on ~1480 finishing date, so I haven't pushed east and into Scandinavia as fast as I could. Another obstacle is reaching Gov 10. I did it in 1453, but it should be possible to make it quicker if taking provinces more selectively (to avoid poor ones). You need around 2 years to conquer Americas (because of diplomat shortage), so Gov 10 will have to be reached before 1448. That's 7 years ahead of time which is going to make it quite expensive. However, I didn't move towards innovative or free subjects - that could help with tech. Generally I didn't bother optimizing economy (since avoiding poor provinces and having to send somebody to take them over again and again is a pain), so one should have faster research than I did without much problem. Whether it's going to be enough to make it before 1448 is unclear.
Now, about pushing east fast. Since you know you need to do it you can prioritize it so that you can immediately walk large army to the province you want to acquire first and assault it. Thus let's say it takes 4 years to acquire it (in practice, in almost all cases it will be quicker, more like 3.5 years). Let's say you've converted into a horde and DoW Timurids in 1412. In 1413 you can peace out and take couple of provinces with adjacency to Rajputana. In 1417 you attack Dehli, in 1421 - Nepal, in 1425 - Tibet, in 1429 - Ming, in 1433 - Manchu, in 1437 - Korea, in 1441 - Minamoto, in 1445 - Japan and Taira. This means you'll get Japan dissolved in 1448. This is right on the limit, but here I've allowed 4 years for cycle, so some time can be saved here. There's also a chance that some fortunate annexations/PUs/vassals will allow you to skip a step somewhere. It's not the only plan though - instead you could just DoW other hordes and take isolated provinces with required adjacencies. It would create problems with moving troops, but shortcutting to reach Tibet quickly will probably work (since you won't need big armies to control it). Alternative solution is to DoW someone (like Rajputana) and take a province from them while you are still not a horde - for example you could do it during the early war with Timurids to get enough armies there.
So I don't see any fundamental obstacles here. However it will require careful management and preparations for each consequent war.