Very hard to give advice without any information on her previous numbers or history. In general, we tell newbies not to shoot under 200, but to wait 20 minutes without feeding and retest. Then if over 200, then you could consider a reduced dose. With that long of a duration on Humulin and you won't be home, I think I would skip the shot and start new tonight at a reduced dose.
And when you get home tonight, ask for help on setting up a spreadsheet so we can see her info at a glance when you want help. If you have trouble just ask for help in getting it to work.