ive gained a bit of experience on this issue. my ex and current gf are great examples; they are very different personality wise, yet made the same moves.
my ex, was an aggressive german exchange student. VERY upfront about her sexuality. on our first date, we were kicked back on my couch, watching a movie and having a drink. she turned to me, asking if i knew what the "drinking brotherhood" was. she showed me to cross our arms, drink. then she says "and we have to kiss." lol, i didnt mind that. we made out for a bit. first date.
my current gf is somewhat insecure. a bit shy, but warmhearted. LOTS of class, high morals. VERY careful upbringing on her parents part. didnt kiss close until second date. even then, she stopped after one kiss. i didnt mind, but later she explained how she isnt the type of girl to make out on the first few dates. i know shes a virgin; i know shed only made out with a guy for the first time 4-6 months before we started going out.
anyhow. point is, two different girls with COMPLETELY different sexualities. but what do they have in common?
BOTH brought up becoming exclusive, after 3-4 weeks of "dating." both questioned what we were doing, albiet in their own way, and where this was headed. both wanted to make it one-on-one.
personally, i was suprised the second girl knew to ask for being exclusive. shes inexperienced, and i thought she expected it to be bf/gf from the getgo.
guess i was wrong =). goes to show that most girls will want you all for themselves after youve established how great of a guy you are. stay cool, let her come to you about the topic. dont force it on her. i understand that a lot of things are a "mans" job to do, but... imo, and in my experiences, this is a move the girl should make. and WILL make, if you are the prize.
and to specifically answer your question, get physical ASAP. even with the shy, reserved gf i have now, she was very willing to make out, before wanting to be exclusive.