I agree with the previous suggestions. You need to be sure your idea is profitable. There are myriad of applications nowadays and many of them don't generate a good business. Once you move to the execution time, get a good team to build a quality app, your testers are your friends.

Be sure to get your IT security strategy in place since the beginning, at least a basic one, when it's easier (and cheaper) to establish. Remember that in the rush to go live many startups lack security mechanisms and a single data breach in early stages can trash all your good work in a minute.

Call me if you need further assistance with the last topic.