I have lunch at lunchtime,around 1.00pm whether it is a sandwich or a full on meal at Harvester.
We have Tea at around 6.00pm.
Dinner is an expression used at teatime 'sit down and eat yor dinner' to the kids.
We dont have supper I've never used that word, it sounds very twee like The Darling Buds of May' .
If we have cheese and crackers or soup after tea because we are peckish its generally a snack. We don't sanck in the evening generally as my portions are filling enough