this is one of those things that different people interpret differently. I use "afternoon" to refer to the time after 12 pm (noon) and before the end of the customary workday (5 pm). I don't adjust my usage based on daylight hours.
I would say simply שבת שלום (Yes, I know, Shabbat is only part of the weekend, but still it's said many times before the weekend. I say it to my co-workers on Thursday, the last workday of the week.)
If you are reached at all hours, whether at work, home, or elsewhere on a single mobile phone, then list the one number under "telephone". If you are reached at work on one number, and on a single mobile phone at all other hours, you might list the two numbers as "workday" and "other times".