This advice may come too late for your meeting, but I think that you have two
roots to getting the best results. The first would be to completely level the
site and then lay an appropriate medium for sowing seed straight onto to ensure
you get a 'clen' start and get a good quality of grass as a basis for the
green. You'd need to reseach/take expert advice as to what the medium should
be and what mix of grass seed you'll need to give you the best results.

The second option is to level the site and prepare it and buy in very
specialised turves from someone who can supply you with the appropriate turves
for your site, soil type, aspect, etc. but then I did assume you weren't going
to use the kind of turves you'd buy from a garden turf supplier. Thought I'd
just mention it though. Taking things for granted is never a good idea.

Basically, I think you're looking at 6 months to 2 years depending on which
avenue you take and how lucky you are with the site, weather, etc.

God only knows if this is any help to you at all, but all the best!

Dave.