There is some rng regarding mails. sometimes they will get delayed and sometimes they wont. you can either get a day 15 credits or day 16. In this run I got day 16 which loses 5 seconds because the other run had day 15 and also 2 seconds to slow menuing
It's a requirement to open 5 slime gates to get the credits starmail (as well as the ancient ruins gate and glass desert teleporter) we skip over them to skip the opening animation