I have been through something similar in recent months. I agree with the above answers you need to set a valuation now. But you also need to set a valuation 2, 3 and 4 years out. Based on EBIT and a reasonable projection. More importantly you need to forecast how much more capital you will need. Take a hard look at what you need to do. Double it. Assume the next round will dilute both you and your co-founder. What will the picture look like after that?