Thermage before PDO Theadlift? Which one first?

Which should I do first, PDO thread lift or thermage? How long should I wait between the two? I’ve had one Thermage session on my lower face and neck, and I felt like it was effective. I have another one scheduled, but I just learned about PDO threads and would like to try that to address my double chin… Which I was just told is not fat but actually sagging skin. I appreciate any advice! Thank you!