May I ask why you have a flame angel in relatively new tank?
Without the presence of a lot of LR
you are going to seriously damage your tanks ability to reduce ammonia and nitrite once you nuke the CC
. Adding a lot of new LR
will cause a ammonia spike by itself.
If this were me, I'd get your LR
up to about 20lbs with a couple smaller increments, and then pull the bed about a month from now. You could always take a chance, do it now, and simply monitor ammonia levels since two small fish aren't going to produce lot of over-whelming waste. The flame angel though would be my biggest concern. Dwarf angels are hardy, but still sensitive to big changes in tank chemistry like any other angel.
You can leave *some* CC
in the tank and dump you sand over the top. With 3-4 inches of sand on top a one inch or less CC
layer acts just as any other inert bacterial sump. It's the sand on top that does the real work. This is form first hand experience converting CC
Live sand will also be much cleaner to work with since adding dry sand to an established tank will make a holy mess, although I'm convinced LS
has no biologic benefit over dry sand. It's simply cleaner when added to a wet tank.