Nice job gaigai! :D:D:D
I find it a bit easier to fold all the inside sewing lines before I start - helps me to get the pieces in the correct places. Sometimes I even write the numbers again, on the 'fabric' side of the paper.
The folding also makes it easier at the end to tear the paper off. And if you get one that gives you trouble, you can spritz it with a bit of water & it will come off.
Good luck!