Workhorse - the instructions say fruit, so they mean the tomato itself. It's not long before the flower withers and falls and you will see the tiny fruit at the base of the flower. If they plants look poorly before that, however, give them some food anyway.

I start feeding before planting my tomatoes as they are in pots for such a long time BUT I don't use tomato feed at this stage - I use a general organic liquid fertiliser. When the fruit start to form I switch to a tomato fertiliser.