How can I project how many users a site will need before it can anticipate robust ad sales?
it depends, in all reality you should ask this to potential investors... as they all have their own criteria. in my experience it has always been 5k to 10k users or dllr amount. that's when your startup shifts from idea validation to growth (emerging business) and pitching becomes easier and more realistic for most angels... the projection again is best to make relations with investors (if that's your goal) so you know what they look for... before you actually need to pitch them... hope it helps a bit ;)
