How long is reasonable to wait before contacting seller?

[boogiewoogie]

That's it really. I've ordered a few items online and am waiting for this one from ebay but I'm not sure what is a reasonable length of time to check whether it's been lost in the post.

just send a quick message asking if they have sent the item yet because you need to know when to wait in for the postie, seller's shouldn't mind an enquiry like that especially as they list what type of postage you are paying for and they want your positive feedback.