you must keep them on the dry side as they done like losts of water. remember they come from hot climates and would appreciate free draining soil. You could use the tomatoe feed but only once the plant has flowered.
Also beware some chillies are abundant croppers so it might be worth looking into how to make chillie chutney or spark up a relationship with your local curry hoiuse. we did this last year and got a free meal out of it!
My chillies are 6inches tall so far and we're in for some good harvesting this year.