when planting a tree, if it's bare rooted, you should use some peat substitute - like Coir - or something like John Innes #3 - don't use garden compost, or manure - it's a bit hot
also, for a young tree, i wouldn't worry too much about feeding it - you want it to get the roots established first
also, having jsut lost £200 of trees to rabbits, if you have any rabbits in your area make sure you protect the trees up to a height of 2'