Sown: My First Flat

On 3/6/2020, I filled a flat of many many small cells, mostly with super small seeds.  I've never done this before, and boy, did I make a mistake.  I must've put too many seeds in.  

What do I do?  I need to look up when it's safe to "prick them out" and repot them.  The row of peas has one shoot coming out, and a ton of spilled seeds.  :)  

I think I'll fill the other tiny-cell tray with the composted horse manure and try this again with the same seeds.  I've kept them sorted into the sets that I've planted, including the peas and beans I sowed outside.