Just a case of patience I'm afraid. They do take a while to get into the swing of things, plus this time of year when daylight hours are reducing, realistically it may be next february/march until they all lay reliably.
Ours are usually good layers during the right time of year but already this year they are tailing off. I think this might be the end of it for this year wait and see what happens when we start getting more daylight again. we microwave our old egg shells and crush them up and feed them back to them which seems to help with laying.
I've got 3 hens (sorry not bantams) and they never lay well from September because they are starting their moult. But in January, just when you think it can't get any colder, the hens seem to notice the days getting longer and WOW you start getting an egg or two from them. Next year Pisky those bantams will make you happy!