If it's not broken then don't fix it A month is a short amount of time on a program even for natural lifters. You can push further with your gear.
Deloading is up to you. We're all a bit different and I think deloading is trial and error. I've done programs where every 4th week was a deload and now I'm doing 5/3/1 and deload every 7th week. Both work for me. I like the 2nd approach because it seems like I'm just getting the ball rolling after the 3rd week and I like to keep going instead of backing off. After 6 weeks of PR sets the deload week is a good mental and physical break.
I've never done GVT so you'll have to listen to your body or just pick a week (every 4th, 6th, 8th, whatever) and plan it as part of your routine. I've also never used any gear so you may not even need a deload.
One thing I'm certain of is that it's not time to change the routine. People forget that a large part of training is psychological. If you enjoy your program and believe in it then you'll see results. If it's a miserable program and you doubt it's effectiveness then you probably won't see results.