these kinds adverbs always come before the main verb.And when the main verb comes with (To Be verbs and can,have/has,...) this kind of adverb comes after them but before the main verb.Also when (were.was.am.are.is) are main verbs this kind of adverb comes after them.
Both are correct in both pairs, but the typical position of an adverb of frequency is after the first auxiliary verb (don't in this case), if there is one. Placing the adverb earlier has the effect of calling attention to it to some extent, which is also fine for when you'd like to emphasize it a little.
I USUALLY do not get up at 8 = "Usually" modifies the whole sentence (It usually happens that I do not get up at 8); I do NOT USUALLY get up at 8 = "not usually" modifies the verb.