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.
Depends on the accelerator, but generally speaking within 30 days of the application period closing. Response times/ranges however are typically defined in the details of the application, thats been my experience.
In terms of helping your chances, thats relative and depends on a number of factors. Referrals from alum and/or mentors are always helpful. However, being a 'pre revenue' early stage startup, traction + revenue never hurts :-)
Hope that helps. Let me know if you'd like to chat further.
Every accelerator should have a very clear timeline on when the application deadline is, when the program starts, etc. At The Brandery, we let everyone know that in person interviews will be within two weeks of the deadline. If you applied and the accelerator hasn't reached out to learn more - an exploratory phone call, etc - then It's usually a bad sign. Most programs read applications as they come in and will reach out to learn more about you. I'd be happy to jump on the phone to share more, particularly around the aspect of improving your chances.