laura, you have a few choices.
1. you can just skip this shot and shoot tonight on schedule. that's probably easiest, but you know she'll be high by then.
2. you can shoot this shot late, say at 10am. but then your next shot is due 12 hrs later, so that would be 10pm. then you have the issue of how to work back or forward to your regular shot time. If she's really high (over 350) at 8pm (+10), you could give her the shot 2 hrs early, but anytime you shoot early you really have to monitor. then her next shot is due at 8am. you don't want to do 2 shots back to back early, though, so you'd have to stick with 8am/8pm for a couple of days and work her back 1/2 hr per day to get her back to 6am.
3. you could shoot at ambg+6 today and then make your next cycle 18 hrs long too. assuming her shot was due at 6am this morning, you could shoot her at noon, then have her next shot be due at 6am tomorrow. that gets you back on schedule and keeps her from being too far off schedule for too long. that's also an easy choice.
I'd probably go with option 1 or 3 if i were you. your choice.
edited to add - i agree with Suzanne that you could take option 1 above, and then shoot a little early if she's high. that'd work too.
