I'm on a bit of a tight timeline (haven't taken the GMAT yet due to some intense projects at work) and with the holidays coming up things are going to get tighter.

But I am still highly motivated to apply for fall 2019. US schools only (Ross, Darden especially). At this point though I would be looking at getting all my material in for round 3 at both schools.

I'm a bit confused about how the rounds work - are there fewer seats in later rounds? I want to put together my strongest package, but I am honestly a bit concerned that I will be too late.

Traditional advice is to wait until you can get the best GMAT score you can to apply. The stronger you are as a candidate, the more likely you'll be to get an admit, regardless of the round.

However, there are some drawbacks to applying later rather than earlier (scholarship money tends to be given out more freely during earlier rounds for example...)

I will keep that in mind because scholarship money would be appreciated!

Good luck!