There is no strict rule on how long you should wait to have a shower after having dinner. However, some people believe that waiting for a little while before taking a shower after eating is beneficial for digestion. This belief is based on the idea that taking a shower right after a meal can divert blood flow away from the stomach and intestines to the skin, potentially slowing down the digestion process.
In reality, the impact of taking a shower after eating is likely minimal for most people, and individual differences can play a role in how each person's body reacts. Generally, if you feel comfortable taking a shower after dinner, there is no harm in doing so. If you prefer to wait a bit, you might consider waiting 30 minutes to an hour after eating before taking a shower.
Ultimately, it's essential to listen to your body and do what feels right for you. If you have any specific health concerns or conditions, it's always a good idea to consult with a healthcare professional for personalized advice.