Well, so it's UTC+2 or more.

guessmyname's Day 0 Timeline:

• the account was created at 18:08 (UTC)
• the first post (D0) at 20:01 (UTC)
• the last acction yesterday was arround 21:10 (UTC).

guessmyname's current Day 1 timeline:

• D0 post was updated at 15:11 (UTC)
• D1 post was created at 15:14 (UTC)

current overall activity hours range: 15-21 (UTC)

source: https://steemd.com/@guessmyname

In case we assume that @guessmyname has a day-based life, then I estimate his location somewhere in the time regions UTC+2 (steemit hours ~17-23) to UTC+4 (~19-01).

Now we need to find a good question which can both confirm that estimate and still further reduce the set of possibilities.
Hmm...