Not sure what the exact minute your insurance starts is, but I don't remember a waiting period.

18 day training pay starts when you get on the airline to CMH for indoc. You'll stay on 18 day pay until you're no longer on an 18 day schedule. You'll be assigned an 18 day line after IOE, and will bid preferences each month until you're bumped off the 18 fixed schedule during the flush bid (I think-flush bid part).