[richy]

I have 11 plants on my window sill starting to flower, should i pinch out the flowers? it is early after all.

[DD.]

No - that's a whole truss of tomatoes you won't get!

[Ivor Backache]

I have got 3 flowering tomato plants in 13" pots to stay in the conservatory and 5 in 10" pots which will go in 13" pots in a cold frame in mid May. Some are starting to set and are all 2' tall. You will probably find others are ahead of me, so it's not too early.
As DD says' don't cut the flowers off....that will defeat the whole object.

Yours are all on the window sill You may want to consider repotting.