how long does it take icing to set?

[fryalot]

properly set so I can ice some words on top without it mixing in?

please?

Am having an emergency birthday cake meltdown moment!!!!!

I don't know if there are different kinds of icing, btw, this was made with icing sugar and warm water and then just slathered on top of the cake

It'll depend how wet it was - if it was very stiff it'll be quicker. You should be able to tell with a gentle nudge if it's dry on the surface at least, but the underneath could still be soft.

super, thanks

could you stick it in the freezer to speed things up a bit? That's what I'd do

If you made it quite thick and with warm water it shouldn't take long, half an hour and it should be hard.