The general rule is always going to be if she's over 150, SHOOT the scheduled dose.
If she's below 150, stall, DON'T feed and test again in 20-30 minutes. Use that time to post here and make sure your subject line is really clear (like "STALLING!! NEED HELP!!" usually works...LOL) You can also put the link to your post on FB to get more attention if you need to.
We have a tradition here. If someone replies to your post and encourages you to shoot a lower number that you're not used to, they agree to stay online and watch for updates until you are totally comfortable with what's going on. Even if it means staying up all night with you. If they can't, they'll tell you up front that they can't stay on to watch you. Sometimes one person will start watching out for you and then if it gets too late for them, they'll either find someone else with experience to take over, or they'll stay online with you no matter what.
If the number goes up, it's usually going to be fine to go ahead and give the scheduled dose, but it's best to get a +1 and +2 the first few times you shoot a lower than usual number.
As you gain more experience and data, you'll gradually learn to shoot lower and lower pre-shots. I did Tight Regulation with China and once I had that data and understood how her insulin worked and what kind of "food bump" she usually got when I fed her, I gradually lowered her PS to where I'd shoot anything over 50. (feel free to look at her spreadsheets)