When is the best time to water plants?

Depends if they are outside in the summer it should be late in the evening. Inside doesn't matter

[i][c=#BF0080]I prefer night for outdoor plants [/c][/i]

Night time or early morning

I'm not super sure about it, but I think it's better do it in the night.

night time has less evaporation

When they’re thirsty

Early morning