Yes, yoga is one of the most effective stress management technique, and from your comments on being willing to work at it, rather than expecting a quick fix, you are approaching it from the right perspective.
To get real benefits, you will need to practice at least 4 times a week. For a beginner, 20minutesofself practice 3 or 4times a week and one or two classes will be perfectly adequate and you should start reaping the benefit of such a regimen within a few weeks.