They sure do look healthy and happy.
I don't know about when to fertilize, although at our meeting last night, the speaker said to let them settle for at least a week before fertilizing. I'm sure someone here will know the answer though.
The speaker also suggested that instead of buying all those special potting mixtures, you just buy the individual components and mix up your own, depending on the needs of your own specific plants. Sounded like a very sensible idea to me.
Good luck with these. I think they're going to do just fine.