What would be a fair division of equity (or the right salaries) when one founder starts the company in his/her basement working to develop the key product of th

What would be a fair division of equity (or the right salaries) when one founder starts the company in his/her basement working to develop the key product of the startup for say 3 years and entirely self-funded over the period and other cofounders join in once the system is sufficiently mature to attract top investors’ interests? (Fundraising was possible before but it wouldn’t get the same caliber of investors / cofounders.)