It can take a while - I had a PPH with my 3rd and my milk never really came in at all - not that huge 'OMG my milk has come in' feeling like I had with the first two. Your body really struggles after a PPH - making more blood for you as well as milk for bubs and it can be so tiring as well. But only being day 2 your milk wont be in yet anyway so don't worry about it too much - if it's not really 'in' by Thursday-ish, then I'd start to worry. All you need to do now is put her to the breast as often as you can.