Next pre release(alpha2 or beta) date of 5.0


does anyone know about the next pre release (alpha2 or beta) date of 5.0 in approximate.

it is ok that not accurate.

I am started to working on a new product based on elastic stack and have to choose e.s. version.

You really should not be using a pre-GA build in a production system!!! There are no guarantees any alpha/beta will be compatible at all with 5.0 GA

Of course I know pre-GA is not applicable for production, also pre-GA will not compatible with GA.
But I considering develop my BETA product with pre-GA and Expect that at the end of the developing I could replace with GA a few month later.
So I am concerned about the next alpha, beta release forecast.