Last year my center was lost in the mail for 6 weeks. I sent a second center so the group wouldn't be impacted so hard. The second center arrived in two days. A few days later the first center arrived. We were overjoyed and it was my first center sent along its way.
Now that little wayward center is lost in a post office in Spain (along with another center she has made friends with).
Don't lose heart. These centers take on a life all their own. They even develop personalities. One hint I learned last year was to always mail in a priority box when sending internationally. But even that doesn't always work.
Also ladies, if you send internationally, fold the quilt top inside out - so the loose seams and threads are showing. Place the quilt - ugly side out, in a plastic bag and tape it shut. Then put the quilt into the box and tape it shut. On the customs form, register it as fabric scraps (which it is - they are fabric scraps stitched together). Then put a value of 10-20 dollars on the form. This will cancel or at least reduce the customs charge.