I saw a screenshot with 42 days remaining.
How do you add more days to the counter?
I saw you post this before, but I don't think anyone knows how to do that. 30 days is more than enough to get an ending with one of the girls. When the 30 days run out, you have the option to NewGame+, which carries over your relationship progress starting from day one (unless you specifically chose not to). However, in order to start off with the side girls, you must have done their H-event and manually asked for sex once (if I'm remembering right), or else they won't show up until they're scripted to. Their relationship points will also carry over, unless you specified for them not to.
I can't remember if the unavoidable H-scenes retrigger in the first few days of NG+, but you should have plenty of time to woo all the girls on your first or second NG+ (though it'll require you to load from saves a few times to grab each ending.) Also, as far as I'm ware, only the family has a harem end. The rest do not.