Got up too early now groggy. Should I force myself to stay up till regular bedtime, take nap or go to bed early?

Depends. If you can time your nap, and limit it to about 45 min (use an alarm) it should not interfere with your normal pattern. If you go down for hours you reset the body clock.
Chronic or acute. If this is a one-time problem, taking a nap may be fine, but going to bed earlier probably is less disruptive and more likely to give productive sleep. The problem with naps is that it can exacerbate the problem--making it harder to get to sleep at regular bedtime, and sustaining the disturbed sleep cycle. Again, occasional disruptions are inevitable, and a nap isn't necessarily bad.