New Project: Wait for Craft 3 or start now with Craft 2? I am just about to start a new project and Craft seems the best fit as a CMS. The projects timescale is 3 months.

I understand that a beta for Craft 3 is due out at the end of this year (2016). In view of this, should i start development on Craft 3? Or run with Craft 2 for now?

The project will involved bespoke plugin development and use of the Commerce plugin. Is there any timeframe in place for updating the Commerce plugin to run on v3?
My recommendation would be to go with Craft 2: 


  A bird in the hand is worth two in the bush


There is no doubt that Pixel &amp; Tonic has turned their focus to Craft 3, but software projects are complex and often take longer than expected and Craft 3 currently only has speculative release dates. It has also had speculative release dates in the past.

If you've made the decision to go with Craft it's likely your additional costs based on the Craft 3 transition will either be to deal with uncertainty and moving targets while developing on Craft 3 for the next several months or to go with the stability of Craft 2 and deal with some extra costs of upgrading to Craft 3 when the transition is well documented and Craft 3 is stable.