New roots are great b/c this signals progression and the ability to absorb more water and nutrients. As for the potential spike, wait till its an inch or so to really confirm that a spike will develop. Assumng its a young plant that is.
I use a specially formulated tropical fertilizer that I use on my orchids. Tropi-grow Orchid Plus 20-10-20 works wonders for me. It so hot every day so I fertilize every day too.