Changing light schedule during flowering

right now in on 9am to 9pm my work schedule is changing in 1 week I want to change to 12am to 12pm so I can tend to the plants.
What's the best way to do this? I was thinking adfing 1 hour of darkness every 2 days
Day 1 off 9pm on 10am to 10pm
Day 3 off 10pm on 11am to 11pm
Day 5 of 11pm on 12pm then 12-12
Will this work with out any harm? Im only on week 2 of flowering

You can just set the new time and leave them in dark for the 3 hours. It will be fine.