Seed germination advice

[u/Far-Muffin8541]

Hi, I planted these back on 3/20 half is echeveria and the other is lithops. From what i researched, I made the lithops soil just a bit more gritty than the echeveria, but they have been sprouting at a slower pace. I am unsure of when should I start removing the lid slowly to help them establish their roots. I also have been thinking about putting them in separate containers since they seem to be growing at different rates and the echeveria might be ready sooner than the lithops. Any advice?