I'm in a similar situation, got two new apple trees that I planted up the allotment in January (ish), All I've done is made sure they're well staked and mulched and I've put some wire mesh around their bases to keep away anything that might want to munch on/pee on/scratch them. They seem to have taken really well and are just breaking out into leaves now.
I wouldn't expect fruit too soon from your trees, I was told to expect nothing until their 2nd season. I'm just going to wait and see. Apparently it's a good idea to get some thick mulch down over the winter time to protect the roots from severe weather