Is this CMPA poo?

Yes definitely, that’s very mucusy which is one of the main symptoms

It can take 6-8 weeks for the milk to completely clear from baby’s body but
you’ll probably notice a big difference within the first 2 weeks, sometimes people notice a difference even as quickly as a few days. I breastfed my baby and it took about 4/5 weeks for the mucusy poos to completely clear. I know sometimes it can take trailing a few different formulas as the one you might have been prescribed might not work for your baby, I.e sometimes GPs first try with milk that still contains milk proteins just very broken down as some babies can tolerate this. Depending on which one you have and how baby is after switching you might need to see the GP for a different milk.