According to the Wrestling Observer Newsletter, the current plan is indeed for NXT to move to FS1 on Wednesday nights once SmackDown Live heads to FOX. The show would air for two hours instead of one and air from 8pm until 10pm.
Now, it's no secret that All Elite Wresling's weekly show is set to air on Wednesday nights so this definitely feels like counter-programming on WWE's part. It's unclear whether NXT will remain in Full Sail or whether the brand will start touring like RAW and SmackDown Live. We also don't know if WWE is planning to air it live or continue taping episodes in advance.
Interestingly, it's said that WWE has been planning to bring NXT to Fs1 for a while but it sounds like they didn't want to finalise the timeslot until TNT officially announced when AEW will air on TNT.
WWE is reportedly confident in the chances of NXT finding success on television, especially as they can pull Superstars from the main roster. FOX will also more than likely push it hard and while this is bound to hurt AEW, it's worth nothing that NXT had Wednesday nights first!