With chillies, if you restrict the pot size, they will crop earlier but with a smaller crop - if you put them into bigger pots they will spend more time growing plant & leaf, but you will get a bigger crop. So why not plant them out into aa range of pot sizes, then you can stagger the harvest? They are definately ok putting a few into a large pot - we do this every year, as every year we over-do the sowing
If the plants are spindly, plant them deeper with compost up to their seed leaves, this will bulk the stem up a bit & make them stonger. Oh, and water in the morning if poss, chillis don't like standing with wet feet all night
