I often put on my togs before leaving the house. (Saves me a minute or two of cooling down before getting in the water). Most important on windy days. I stay warm as long as possible. Uncomfortably warm is good!
How do you feel in the water?
How are your fingers/feet?
What are today’s conditions?
Are you having fun? (After all, isn’t that why you’re doing it?)
Get dressed as quickly as possible. Try to be dressed within 5 minutes.
(Have something stand on while getting dressed. I use a €2 rubber car mat.) Choice of clothes is important. (Anyone used to outdoor pursuits knows denim isn’t good. It does not retain warmth and is particularly bad when damp.) Hat. Gloves, etc.
Warm/hot drinks are psycholoigically comforting, but pretty useless for rewarming. The discrepency in temperature between body & drink is far outweighted by the fact that the body weighs a couple of hundred times what the drink does. For drink to be effective in raising core temperature, one would have to drink a couple of gallons.
Wearing clothes that trap & retain the maximum radiated body heat is more effective. As is exercise, which will raise your temperature internally (exothermically). After a cold swim you will only need moderate exercise for the effect so a walk is good.
Why not? You measure it, it will get better.