You're required to wait a minimum of 31 days, and we recommend that you plan in at least one re-take just in case, so that's where the one month idea is coming from: you need to give yourself a minimum of on month for any potential re-take.
There are two broad scenarios:
(1) You got almost the score that you wanted but you're looking for a little more and just need to tweak some things to get there. Typically, those in this category aren't looking for an improvement of more than 50 points. In this case, ideally take the test within about 4 to 6 weeks so that you don't lose momentum.
(2) You're decently below the score that you wanted and you need some significant work on content, timing, or both to get to where you need. In this case, you're looking at 6 to ?? weeks, depending on the distance that you want to go and the amount of time you have to study.