I'd agree with the others that it's a good idea to just try. Anyway, even gaining 5$ a month from it is better than getting nothing, right? So what's there to lose?
In addition to this:
If you don't have the time to do two stories at once (I know not everyone can), then maybe try to prepare the next one while the other is starting its ending phase. Like, already tell your readers about your idea, maybe give out some information on characters/setting, a temporary blurb, the working title, the cover art ... Whatever you can think of to get them interested in the next story already and then start to post shortly after the other one is finished.