if it was just one day it shouldn't be a big deal, especially because the 18/6 period isn't exactly "stressful" or at least in my opinion it is not stressful in the way that generative phase (flowering initiated, for example, by a 12/12 lighting regimen in photoperiod plants) is, I don't think you should have any issues. Especially if you are going to be in 18/6 for a while.
Always good to proof your timers though. You can always turn them (dial style) or push the clock hours forward (digital) and watch it trigger through your cycle. I do this after everytime I set a timer, especially the digitals, you never know how a different brand might be setup, some of them will not start a set cycle until you hit the "time and day" that you tell it to start. For example it is tuesday night, 8pm and you have a program to cut the lights off at 4am and back on at 10am, you set it up tuesday at 8 expecting the lights to kick off at 4am wed. It doesn't happen, they stay on and then "click on" at 10am when the program finally starts itself on wednesday morning, from there it would run fine. You could prevent this by just pushing the hours forward/back so that before you leave tuesday night you have run the timer back to 9:59 tuesday morning, waited a minute for the program to engage, then push the time back to 8pm or whatever the real time is, and the program will correctly turn the lights off at 4am wed. Hope this helps ya bro---was kinda betting this is what happened to ya
MPP
