It would be so much easier for everyone, if companies would IPO earlier. Evaluation of your option value would be straightforward, there is liquid market, no need to worry about investors preferences, ratchets, etc. Also the whole market gains a lot of efficiency if basic financials are public. Not so long ago, companies used to IPO way earlier... Microsoft, Apple, Amazon...
This is a good read too
http://thomasgr.tumblr.com/post/135710601255/the-pre-ipo-dip...