What may be most important about your language learning regimen, Rachel, is spreading the three hours throughout the week instead of cramming it all into one weekly session. Thirty minutes daily - only three and a half hours per week - would give you the repetition that is really essential to learn and to retain a language.
As for Wheelock's - I worked through most of it on my own. You'll find that it is a decent aid to learning Latin. However, you should be aware that there are a lot of critics of Wheelock's, both among those who study Latin as a hobby and among professionals and academics. You may wish to consult the following thread: http://www.textkit.com/greek-latin-forum/viewtopic.php?t=53
In my own opinion, by all means use Wheelock's, especially if you have it already. But you should supplement it, either with another contemporary textbook (consider especially Moreland and Fleischer's Latin: An Intensive Course and Hans Olberg's Lingua Latina--these represent two radically different methods of learning the language) or with one of the FREE textbooks available here. See this thread for more information: http://www.textkit.com/greek-latin-forum/viewtopic.php?t=2370
The primary rational for this approach is that Wheelock's 1) simplifies many of the concepts and constructions of Latin and 2) does not provide enough examples to thoroughly immerse you in the language.
If you have any further questions, we will be most delighted to have a go at them!