Highly agree with this answer. However,this won’t take 1/2 hr a day.. dry fire from the holster the head shot 20-30 times every other day. Then go up to 50 times every other day..no timer..if you feel like you want the head shot 1st, then this will help.
Then hit the range and do head shots only..try it out.do not worry about your time. Consistency and visualization is the key.
When I was live firing a ton years ago,I would start with 6 head shot only on 2 targets at 20-25 yards. Then my last 6 rounds for the day are head shots at 20 yards.