Hello good people hopefully you are enjoy some nice spring (or fall) weather in your area.
I found a yoga class that is advertised as 15 minutes of guided mediation immediately followed by the Ashtanga primary series, a very physically active practice. It is just a regular type class open to the public. I was hopeful that some could offer their opinion on this. Meditation before Ashtanga primary? Would this be a contradictory or harmful combination? Particularly in this order, meditation first. And why? I really try to keep an open mind but I have never heard of this before. And I should also mention that I am proficient in the primary series so that is not an issue. Thanks.
The order sound right in the situation you describe. It is not recommended to do strenuous exercise right before meditation. Since the asanas in question are physically demanding, it's better to have them after meditation.
What you should know is that guided meditation is a very watered down form of meditation, so don't expect a lot from it in the long run. When we meditate, we want to go inwards. Having an external voice talking at you throughout your meditation achieves the opposite result. It doesn't mean it can't be enjoyable (that is if you have not got used to a more effective form of meditation), so if it tempts you, go for it.
If you want an effective meditation method, read Lesson 13.