AI need to make about 300 small royal icing flowers for a cake due at the end of the month, how far in advance can I make them, to where they're still fine to eat? I'm a bit funny about food sitting out too long, spoiling, etc. so this is something I just don't know? But of course if I can make them in advance it would be nice!

And, how should I store them once made?

Thank you!

I believe you can make them when you want, Royal icing gets extremely hard so I dont think it will change if you make them really in advance. But make sure to store them in an air tight container and leave them out of the light.

My grandmother used to always decorates cakes, and I believe that she would make a lot of flowers and but them in airtight containers and then freeze them so they would keep longer.. but I would say as long as you store them in an airtight container once they've dried they would be perfectly fine at room temp until the end of the month. 

AI don't think there's any need to freeze them.

AFreezing them introduces moisture and they will just fall apart. Once they are dry layer them up with kitchen paper and put then in a box and store away from moisture they will keep for years

When I 1st started decorating I made up 100s of royal flowers and kept them for as much as 2 years :(  No they don't do well that long :)  But they certainly will keep fresh for a couple of months.  Do NOT freeze them.  Just keep at room temp in a covered container out of light.