As someone who just started growing again after 10 years of not being able to due to space issues, and was a bit of impatient with it so didn't wait for my pots to arrive and just used some shitty ceramic I had around the house with no drainage, I can tell you that you might end up regretting it if you repot autos..
- 2 of mine ended up with stress damage, that turned them into hermas.. Luckily my 3rd one isn't showing the same signs tho.. But she's only in preflower while the other 2 went into flower a week early.
Just add some extra soil to the top.. Plants are surprisingly adaptable to that, they'll sprout roots from any part of a stem or branch, that are borrowed in grow medium, and it won't cause them a lot of stress either.
About the plant getting root bound.. Don't stress too much about it. That's one of the benefits of the fabric pot.
- The root bound is caused, by the roots hitting the sides of the pot, and then growing around in circles.. With a fabric pot, the roots grow to the sides instead, and then stop growing due to the air hitting them, which causes the plant to expand the network, instead of focusing on a single long root. (It's generally callled air pruning)