Starting Test Cyp 100mg/week after losing 17kg on Reta. Dose & muscle gain advice?

Hey everyone, first post here
I recently lost 17 kg using Retatrutide and I’m now shifting my focus to building muscle.
I have Testosterone Cypionate at 250 mg/ml and I’m planning to start with 100 mg per week, split into two injections of 50 mg (Monday & Thursday), subcutaneous.
Just to confirm: on a standard insulin syringe (U-100), 50 mg should be 20 units, correct?
Second question:
What recommendations do you have to maximize muscle gains on this dose?
I’m currently training 4x per week and eating as much protein as I can. Any tips on diet, training, or other things that helped you the most when starting low-dose Test?
Thanks in advance!