DIY Pop-Up Thank You Cards

I'm finally finished with my Thank You cards! It takes only 4 steps to create this simple pop-up, here's how:
1. Trim liner to fit inside card as desired:
2. Fold liner in half and make 2 parallel cuts perpendicular to fold line (size and location as desired, I chose 1/2" to 2/3" cuts with matching length apart):
3. Open liner and push in fold from the cuts:
4. Glue on desired cut out on the fold's front face:

Viola!

The front of a couple of our cards:
They open up like this (yes, one of them says 'many thanks... for being Awesomest Prime!'):
Photo+Quote cards from the Marriage Celebration Tree are also included with the corresponding TY cards:

I recycled as much materials as I could from the wedding. The signs contributed much to this project:
I used tape instead of glue to secure the signs so that I can reuse the paper and ribbons:

I tried several looks before I ended up with the relatively-easy-to-mass-produce versions you see above. Sewing paper is a huge pain in the butt!
Sealed with some left over wedding stickers from my cousins wedding :)

Paper is my least favorite craft so I procrastinated on these forever (hindsight, I really should have outsourced this). 5+ months after the wedding and I'm just now sending these out! I once heard that I had up to a year to send them out, so I've been holding on to that excuse all this time. It ain't pretty, but it's done! Woot!

When do you consider a TY card late? Are you giving yourself a time limit for sending out thank you cards?