I've been typing on Italian QWERTY since I started using computers. I was 5, and Windows 98 was the lastest Microsoft OS around.
After becoming a programmer I noticed the Italian keyboard was pretty bad for devs..
The need to use AltGr in order to type @ # [] {} is annoying.
So I switched to US qwerty for a few months, until my wrists started to hurt. Typing 5-6 hours a day everyday with a qwerty is painful!
I tried to switch to Dvorak, failed, and I tried out Colemak: it felt tremendously good since the first minute.
4 days later, I was back at roughly qwerty speed. Never officially speed-tested,though.
I didn't need to print the layout, I just switched around my IBM Model M keycaps:
...And started typing.
I set Colemak as my only keyboard layout both on my Windows 10 and Void Linux, and finally I can say I find typing a pleasure.