Are the ideas still in your head? Or have you written a plot line / synopsis?
I have observed that it is often easier to edit, and add to something you have already written, than it is to craft that important first sentence.
Get the whole story down and then start moving it around till you get a good feel. Sure it might be time consuming, but the time is passing anyway
Voice recorders and speech to text tools can be good for just getting your ideas on the page.