This depends on how much battery life you have on your laptop. If Windows 10 is already downloaded onto your laptop and is installing from there - then it usually takes 45 minutes or less. It is annoying that Microsoft forces the update but I am surprised you are running into this issue because they stopped pushing the update some time ago. If you absolutely need to take you laptop then I would say "It is what it is." and take it with me. If the laptop dies you run a risk of things getting corrupted but it shouldn't make your laptop explode. Worst case scenario is the laptop dies and you have to get your old files back using an external enclosure (or boot disk) and reinstall Windows.