Coleus Plants speak when they are dehydrating...The Gorgeous leaves will *flop*..water ASAP, warmish/coolish water, the Leaves will perk up in about 30 minutes or so.
If your cuttings flop while you have them in a jar, pot, etc. of water until they Root, you should snip the bottom of the stem about a 1/4 to 1/2 inch, and snip off any Large Leaves. This will assist in perking your Cuttings back up..Place them back into the water, change water every 48 hours.
Spring Summer, more Coleus to come.