We are a pre revenue early-stage mobile app startup
Each accelerator is going to be different so there's no typical wait time, but here's some basic advice:
1. You can't count on getting in, so you must continue growing your business as you would without the accelerator.
2. Ask your other entrepreneur friends who applied at the same time if they heard back yet. If so, definitely follow up with your contacts at those accelerators
There's not really much else you can do to improve your chances now that your applications are all in. You can try some "stunts" like sending 500 cupcakes or something else to grab attention of the partners (you can find stories of stuff like this working for people), but in my opinion these are more of a distraction. Just focus on your business.