The pods usually grow to a certain size then stop and sit for at least a couple weeks before ripening, but longer for chinense including white habs.
Length till full size varies greatly. Depends on sun, nutrients, temperature, # of peppers trying to grow simultaneously vs plant size and ratio of leaves to stems to attain that size.
Fortunately with white habs, they are reasonably edible even if picked at a creamy yellow-white color instead of the almost if not completely pure white that they'll eventually turn to, but don't pick them the moment they turn yellowish or they won't be as hot and will be too crunchy/firm to enjoy raw.
Those I've grown did not get longer then fill out, assuming you mean the pods not the plant itself. Well, maybe a little bit but not a lot.