You know, when it comes to seedlings. What I do is plain & simply this: damp a paper towel (not soaking), scratch each bean against a match box striker. to kinda break the seal on each shell/seed. I then place them in a zip lock bag (not sealed). Then on top of my fridge, or x-box they go. Heating pad would work to. I try & make sure they don't get TOO hot though. Usually in 4 to 6 hrs I see tap roots. Some have took longer though ( 2 to 3 days max). Then once taps show I make me a little hole in my medium, careful not to damage tap upon insertion.
then I place the zip lock over my little seedling container (gives greenhouse affect). Most cases I see green in just a few short hours.