Baby initially rejecting Nutramigen

I just wanted to post this because I was frantically searching for someone else in the same boat as me and couldn’t find the answer! My 3 month old son was prescribed Nutramigen last week and I went to give him his first bottle and he gagged and retched and would not take it (I then cried for 2 hours because I was convinced he would never take it and be in pain and never sleep ever) after a while he took more and after a few days we have noticed a massive difference and is taking full bottles. We didn’t put any vanilla essence or his old formula in like some posts on the Internet say he just got used to it with perseverance! Don’t give up hope if you go through this too they will get used to it 🥰