Warm up while queueing
Start searching for a competitive match as usual.
Then, open up the developer console (set to ' as default) and do as shown:
map de_mirage / just press ENTER
map aim_botz / full name of the map will show up, select it before pressing ENTER
map workshop\ / the maps you have downloaded will show up like this:
The map will then load and you'll be able to play until a match is found, when the message to accept will show up.
Don't worry if you're disconnected from the match and are forced back to the main menu.
You'll be able to quickly reconnect from there.
If you have any questions, feel free to ask them below! I'll try to read every comment and help when possible.
Thanks for your time, I sincerely hope this guide helped, and please don't forget to rate it!