I dont tell people how to hold a bow BUT that 2nd pic is how I hold but I keep my fingers together and my thumb pointed out alittle more away from the riser and the grip just balances between my thumb and pointer,then on release it just canters forward alittleand the strap keeps it from falling to far....been shooting like this for just about 20 yrs(thus the wrist strap),the 1st 4 yrs I griped the bow due to the fact I didnt have the wrist strap.......
Too this day I cant see how guys grip the bow with fingers on the riser.....kinda like your 1st pic......