Hi.......Bottom heat will definitely help inspire your caladium to sprout. Just be careful that the high heat doesn't dry out the soil too much, because they also like damp (not sopping) medium. You might check to see if a medium or even low setting will do the trick.

I have mine potted up, too, and sitting on a heating mat, trying to get an early start this year. I just planted them on Sunday, so am not expecting to see anything for another week or so.....Good luck!