Should I put a 4 month old in 120 gallon?

So my baby is 4 months old and I have her in a 40 gallon, recently I got a 120 from my brother. Some people are saying to wait until she’s bigger cause it could overwhelm her(that’s also what her vet said) but others are saying I should go ahead and just put her in it and I know some vets are wrong. I’m very confused on if I should or not 🤔 I may just put her in and she how she does but if she doesn’t like it I’ll put her back in the 40 until she’s bigger.