My experience with guys who have not had sex before tend to go way too fast and want to be inside me after only a few minutes of foreplay. Experienced guys with the right intentions go a lot slower and wait until the girl is fully aroused. So go slow, and let her step the pace. She'll let you know when fully aroused.
Kinda surprised you've been together 6 months and only now are consider sex. I'd wonder how strong of sexual chemistry a couple has if takes that long. I don't jump into bed with just any guy, or do it right away, but if I really like a guy and he likes me, even a couple of months would be a long trial period to see if we like each other enough to have sex.