For those of you who have experienced Ondari Lifting, is the firming effect clearly visible even on faces that don't have much fat?

I have an alumni gathering scheduled for next month for the first time in years, so I’m planning to start taking care of my face. I get so stressed whenever this time comes around. I’m scared of bone-cutting surgery or invasive procedures, so I’ve put On-Da Lifting on my list of options because I just want to naturally slim down my jawline. I don't have a lot of body fat; I just have a slight double chin and my side profile is a bit blunt. I want a clean, defined line without it looking excessively sunken. For those of you who have experience with On-Da Lifting, does the firming effect show up properly even on a face that isn't very chubby? How long do the effects usually last after the procedure, and is now the right time to get it done, a month before the gathering? I’d appreciate your feedback.