Felicia
Okay. You're looking for various symptoms, like shaky hands, nausea, excessive sweating, anxiety, headaches, insomnia. If any of those are things he experiences normally, then look for anything different about it, or if there's a new combination of things.
There is the more severe end of the scale which can include hallucinations or seizures.
The first 12-24 or so hours since the last drink is when you should expect the milder symptoms, that's the last of the alcohol leaving the blood stream. After the 24 hours, then it's time to really look at how he's feeling and if he's going to need something to help his body adjust to the lack of alcohol. There are medications I can give him if he's experiencing high levels of any of those symptoms.
Generally speaking as well, make sure he's hydrated, things like blood sugar and salt levels are reasonable. Follow your instincts, if things feel wrong then call me and I can come over straight away to help out.