Honestly, I would have started doing it at aboput 3-4 months post if I had thought about it sooner. I actually didn't start to braid my hair until about 7-8 months post. But again, you do NOT need to wait that long. The sooner, the better and easier.
When I wash, it isnt as difficult as it use to be, also, the relaxed hair isn't fighting with it's natural state because the two are seperated.
If you have time on your hands, I say try it! Let me know if it works.