Welcome @jeholder, I can certainly relate to sometimes not drinking enough water. I think the answer to your question is it depends. For me, I've usually felt better the next day after drinking enough water and other fluids but I just had some cramping along with a headache. Here's some information that you have probably already seen but it does cover the topic.

"Recovery time for dehydration depends on the underlying cause and may also depend on how long you’ve been dehydrated. If your dehydration is severe enough that it requires hospitalization, or if it’s accompanied by heatstroke, it may take a day or two before you can be released from the hospital."
--- What Does It Mean When Dehydration Becomes Long-Term and Serious?: https://www.healthline.com/health/chronic-dehydration

Are you still having the nausea? Have you thought about talking with your doctor?