In my opinion, if you have cofounders, you should split the equity evenly. If you are uncomfortable splitting ownership evenly because you don't think your cofounders will work hard enough in the future, you probably shouldn't start a company with them.

If you're concerned about fairly valuing the work put in until now, a month's work, even if you had done 100% of it yourself to date, is a small, small portion of the total work required to get to cruising altitude. This is a multi-year journey, after all.