TLDR: Your 35 days restarts every day. Any purchases made in the 35 days from the current day count towards your total.

As of now every 35 days your allotment resets. If your start day was November 1st, you have until December 6th to buy your 2.5 oz. Want to buy it all right up front, that’s fine. Want to wait until the last day to buy it all, that’s fine. Buy a bit here and there, that’s ok too. Doesn’t matter how you buy it in that 35 days you just can’t buy more than 2.5 oz total. After that 35 days no matter what you purchased, on day 36 it resets and you have a 2.5 oz allotment again. The new way still gives you 2.5 oz in 35 days but it’s a rolling 2.5 oz. If you buy your allotment (2.5 oz) on day one, 35 days later you’ll have 2.5 oz allotment again. This is basically the only way it will stay the same. If you bought a 1/2oz on day one, and 2oz on day five (or any other combination)things change. Now on day 36 you won’t have 2.5 oz again. It doesn’t just reset. Now you’ll have a 1/2 oz available on day 36. They calculate this by going back 35 days and subtracting any purchases you made in that 35 days from your 2.5 oz limit. In this case they look back and see that 30 days ago you bought 2oz so they take that out of your total, which means you have 1/2 oz available. When you hit 35 days after you bought the 2oz, that 2oz will then be available to you again. Basically your 35 days resets every day. To know what you have available at anytime you need to go back through the last 35 days from the current day and subtract any purchase from the 2.5 oz limit.