My H1b starts from Oct 1 2018 and is valid only for 16 days Oct 16, 2018. Can employer file h1b extension before h1b starts? I will get client letter not more than a month ahead that is around Sept 16, 2018 for job extension. How efficient is this time frame to get response in time using premium processing. I will have to get response before my h1b expires I guess and not sure if you can continue working.

I am also thinking not to accept the h1b and keep my stem ead.
In that way I can talk with my employer for direct gc processing since my stem ead is valid till 2020 June. I feel this is better option with current system of h1b date which will be based of the project date.
I will appreciate everyone with suggestions.