Lower face volume loss - how can this be treated? (Photo)

With a 6 week time frame, you definitely do not want to do any surgery. Energy devices such as HIFU take months to see results and may not even address your issue. I think the perfect solution would be a Y_Lift procedure. This is where fillers are implanted onto the angle of your jaw to bring back your jawline. This should help reduce the rolling in the marionette area and also give you a snapped jawline. The results are instant and can last for years and there is very little down time so you can be all set for your occasion in 6 weeks.

You may want to consider Morpheus8. This treatment combines RF technology with microneedling to improve overall skin tone and texture. This can be combined with fillers to give you a more complete result. I've included a video I hope you find helpful.

The fastest way to address this concern is to use very low G’prime hyaluronic acid on those area. Care must be taken not to over do as it can lead to puffy look.
The underlying cause of this concern is not just volume loss but also a weakness in the skin integrity leading to dentition especially during muscle contraction (such as smiling). Unfortunately, this will eventually lead to deep wrinkles and can be permanent as we age. My preference is a combination of low G’prime hyaluronic acid and biostimulator to enhance your own collagen production without fear of appearing too puffy. Biostimulator together with skin resurfacing and regeneration can further enhance the outcome.