I work some weeknights, plus large chunks of the weekends. I get maybe 10-20 hours a week on the project. I find this approach quite frustrating, though: you get totally in the zone and then it's time to go to bed because you have work the next day. Also, I find that I no longer have so much energy for volunteering or writing music or socialising. I knew that doing a start-up meant saying goodbye to your life, but I didn't realise that sacrifice would have to be made so early.