Should I wait to quit with MSc or quit right away
Look for other opportunities whilst still continuing with your PhD. Hopefully you find something by the end of your masters year and you can part ways then. 

If you can go to an employer and say you're in the middle of a PhD but have realised it isn't the path you wish to follow and are looking for other employment it looks better than dropping out and then looking for work.

Also, not that I'm trying to change your mind but, I don't know a single person doing a PhD who hasn't doubted it was the right thing for them at some point. Make sure quitting isn't something you would regret later in life and think about the reasons you chose to apply for a PhD in the first place.