I get around 30Mb per minute.
You can always upload before you go to work or school and set it to public when you get back.

One of my Videos is between 1 to 1.5 GB and my Internet is also very slow i'm uploading during the night. Or some day on my mini passive PC which makes 0 noise but first i have to set it up x.x

Mine makes too a lot of noise i'm annoying myself with it but i have no time to setup that mini pc ._. I had the luck that we had a customer which stopped with their work on special PC's so i could get that mini PC it's like a raspberry Pi maybe you should buy one of these and set it up as youtube Upload Terminal. I think i've seen already Tools to make a raspberry to a youtube upload Server only.

I keep my videos around 15 mins long, and I set the bitrate to 8 so the file size isn't too much (around 700mb). That's around the normal size for videos like this. I either export in 1920x1080 (1080p) or 1280x720 (720p). Good luck with your channel!

... you mean you're making your videos with camtasia? *facepalm* ... that's the worst what you could do... bad vid quality at large filesize. My 1 GB are on 2048x1152 in best quality with 20 - 30 mins

For myself, I use Screenflow to record/edit/export my videos. The screenflow file is around 20gb(it's cause it's full of other videos I post at the end of my video). I export at 29.97fps(it's what YouTube uses, so if you export at 30, it's gunna take extra time to encode.) I also export it at 5500kbs(that's if you're going to export in 1080p. My files afterwards are usually around a 1gb or 1.5.

Videos length from 10 to 30+ minutes 1080 tend to be anything between 1gig to 4 gigs for me. General rule of thumb seems to be every 10 minutes = 1 gig with settings I run.

10 minutes of 720p around 200-300 mb.