Does anyone use Aptimal Pepti 1?

My little girl has been prescribed aptimal Pepti 1 today due to intolerance to cows milk protein symtoms ... 

has anyone has had their milk changed to this before and how long was it before you saw a change? 

She normally gets upset after feeds especially around this time and she has had a feed and gone straight to sleep! Surely it can’t work that quick! 

thanks in adVance x