I’ve read different accounts of the Nixon drinking. Some say prior to entering the White House...he was just an average consumer of alcohol, and mostly all after dinner. Then they seem to say that about six to twelve months into the administration...around lunch, he’d just start to consume two to three cocktails. By the third year, if you had something important to talk over with him...you had to do it prior to lunch.
That sounds about right. I suspect the whole Watergate mess made him take refuge in the bottle. On the other hand, given the lying press, it might all be made up!