Don't know if anyone has already mentioned the dreaded "meter variance" to you or not....
Meters can have a degree of error/variance of up to 20%. That 364 you had yesterday morning and the 407 you got today could in fact be right around the same number. I know that is frustrating, but you do have to keep it in mind, especially when considering changes in dose.
From what I have seen, the more "constants" there are, the easy it is to keep things straight in your head. One of those constants is with dosing amounts. It is best, especially at the start of treatment, to keep the doses AM and PM the same. What you don't want to do this early in the "dance" is to start "chasing" the numbers you are getting. I agree that her PM readings have been lower than the AM readings. But, it's only three days of data, AND you just are starting a new insulin too.
For now, my advice would be to go ahead and start her on the Prozinc either now, or after you go away for that one day. And, keep the dose at 1u for now, AM and PM, with a possible reduction for those two shots you know you aren't going to be around to test for.
If you start the prozinc now, we might have a good idea by then what that dose should be. If you decide to hold off until after your trip, then we can try to determine what the dose of the Humulin should be for those two shots.
But I would not, no matter which insulin you use, start shooting different amounts AM and PM. Like Mel said, sometimes you can manipulate BG levels using food and timing of meals, which is easier than making dose adjustments. And the important point she makes is that when you do decide to raise or lower, you should do so in little amounts like .25 or .5, not in whole units at one time.
Carl