It won't hurt anything if you just leave it, I have no idea how long mine went unglued! Here's my thread from last year when I discovered this strap and found the velcro had come unglued -
http://986forum.com/forums/boxster-general-discussions/63292-question-convertible-top-strap-service-position.html#post511134
And here's a picture of the strap I found on Google, this is probably from the owner's manual. (I've never read mine either!) I would have taken a picture of my car, but I'm a bit under the weather today.