Maybe you should read your seed packets more

I'm pretty sure it would tell you days to germination on the seed packet....
Rosemary cold hardiness depends on the variety. Most are hardy to zone 8. Arp and Madeline Hill are rosemary varieties that have been bred for cold hardiness. They would definitely be hardy in zone 7. I haven't tried the Madeline Hill (maybe I should) but the Arp though it says it should be hardy down to -15, did not make it through my zone 6 winter.