It depends on the person, but the general rule of thumb is that if it's really difficult/painful/prolonged to get the dilator in after a stretch of skipping, that was too much time off. (For me, at 2 years post-op, I have *just* gotten down to the once a week my surgeon recommended. Even a day longer than that and it still hurts a lot.)
At six weeks, I'll second everyone else - it's SO new and healing that the rules are different than they will be a bit later on, and you really don't want to risk it. I don't know anyone for whom it closed up completely, but there are several stories on here alone of women who skipped a couple of days and had a ton of trouble, or who were in so much pain that they reduced dilation frequency and within a couple of weeks had to consider being surgically re-opened.