When I have nothing else on my mind, and nothing else I need to get done.
Which means, rarely.
When are you in the mood to play your best?
Sort:
In an OTB tournament. You're really not thinking about anything other than chess whereas if you're playing online you can have 10+ unrelated tabs open
In the evening you dont have to think on other things. For me it works better...
The big joke of course is : " when my wife is not at home ", but, before answering the question, I want to repeat what I said in another forum, the opponent makes the level as well, I play better against higher rated opponents, some beginners cost me a lot of time ; moreover, living in Holland clearly makes a difference : in the morning more players from e.g. India and in the afternoon more from e.g. the States, both regio's differ six hours plus and minus.
I don't make notes on who is better, east or west !
Being retired, I'm always in that good mood to play, just in between shopping, cleaning the garden, going by bike and a lot more...
I notice sometimes after getting a good nights sleep, if I play chess I will actually play worse because I'm full of energy and want to go do something besides stare at a screen.
And sometimes if I'm a little bit tired I'll play very well because I'm in a sluggish mood and don't rush anything.