Depending upon which chart you pick, be careful as not all agencies use the same number of letters in their tables. For example, some tables only use A through L for their pressure groups, while others may use A through W or more. So the difference jumping from one group to the next may not be what you're used to if you use a different agency's table. Not that you can't use the other agency's tables, but just be aware of this.
Another thing that I've seen overlooked before is while you can figure out how long you need to off-gas before going diving after driving UP to a lake, don't forget that you may need to off-gas before driving back home if you need to go over a higher altitude pass to get back home!
The best suggestion, as stated above, is to get some training from an instructor. It's not that complicated but there are a few things you'll need to be aware of for your safety.
Enjoy the lakes!