I wanted to take the measurement approach (with a fitbit) but I quickly discovered that it was mostly metrics difficult to measure (how sluggish did I feel that day? was my weekend spend in bed? ...) so I kept a journal and resorted to trial and error.
Initial plan was to wake up ealier by 30min deltas every other day but well it's not a sleep study: I had a daily job to attend so I was a bit limited there. Also I was on the search for a permanent solution, so I preferred testing a wake up time at least 2 weeks before seeing if it fits or not.
From then on, I knew already that 6.30am was hell and we had 2 weeks where I needed to be early at work so I shifted my wake to 6am. I noticed it was quite a lot easier to get out of bed; mind you not a celebration or anything but noticeably easier.
For the second part, it was more a shot in the dark as I basically took the difference between a good wake up time (8.30am) and a bad one (6.30am) which led me to believe that the next good slot was around 4.30am. Which was verified again over 3 weeks. I tried intermediary times and they all proved to be worse than those "sweet spots".
One thing though I tried to smooth whole wake-up process so I prepare now everything the day before (clothes, mug, laptop, ...), I have this light box in the bathroom that's like a little sun, I bought a "real" coffee machine, ... and I go to bed as soon as I yawn a bit too much (~10pm as said earlier).
Hope it helps!