Tomato Feed

I am experimenting with different tomato varieties this year as I want to make puree, soup and chutney etc later in the year.

I am going to grow them all in the greenhouse as last year I had trouble ripening them before the weather changed, and I am going to grow some in grow bags with the grow pots in and some in large terracotta pots. 

My question is they are all just beginning to flower so I am now going to plant them in their final positions but I would like to know about feeding them.  Should I feed them now before I plant them or wait a while longer, also should it be a full strength solution or a half strength and what is the best food to use.

Sorry, a lot of questions there................