How do you keep from moving too fast in a relationship when the chemistry is sickk!?

i feel like i just met this guy but i really like him, feelings mutual, i met him like this week. but i thought he was really y, plus he knows someone from my school and lives in the neighborhood, so at first i gav him my # to keep in touch. now i like him and he wants me to be his girlfriend, but i feel as if its moving kinda fast.. i almost kissed him... how can i slow it down a bit or am i moving at a ok pace... i knew him for only a week! but he is a really kool guy and we laff and get along great we have even argued before and made up lol.