how long does it take to charge magic keyboard and mouse 2

Charge them while you sleep and you have no down time during the day. From the Finder menu bar, you can click on the Bluetooth icon, locate your device, and check on remaining battery percentage.

You are never in trouble with these.

Like dialabrain said, 2 minutes and you should have basically a full day's worth (or, with the exception of the mouse, you can even used it while plugged in).

Then let it charge overnight, like VikingOSX said, and it should have charge for months. Incomparably better than the original ones, which I have (when I have to reach for a pair of extra batteries, more often than not they are not charged...).

I read somewhere 2 mins to charge the Magic Mouse 2 for about 9 hours use.

If you already own them, plug them in and time them.