There is no “typical” when it comes to magic, it can take minutes or it can take years. Also depends on a few factors like the strength of your intent in the spell, and how many factors are working against you (i.e. your ex being angry at you); magic tends to take the path of least resistance, it can take longer to manipulate circumstances in some cases.
Also there are other demons you can call on – Orias might be a good one, or Sitri, or Dantalion.
@RoyalAquarian I appreciate you have strong views on this but moralising isn’t really helpful to the OP.