How long before AF does it drop?

Today is 10DPO and according to my LMP, AF is due today (yes, short LP). She's not here yet. Yesterday I checked CM and got one glob of CM streaked with red blood. But that was it. Never had that again, nor did I see spotting on TP or underwear. Today, when I check CM, it's a little brownish, but again, not showing up on TP or underwear--only when I check cervix.

The weird thing is that my cervix is high (and firm). If I'm going to get AF today shouldn't it be really low? I'm hoping this means my LP might be longer. I know I'm not out, but I think the CM points to AF arriving soon.