How long is reasonable to wait for dispatch?

[AntiHop]

I paid for an item on Saturday. It's now Wednesday and they haven't dispatched it. Should I send them a message and remind them? It's someone selling bits from their own home, not a shop.

Is it fair to leave a less than glowing review for being left waiting?

Yes I would contact them. What was their despatch time set to on eBay. When I sell, I try to despatch that evening but have mine set to 2 days.
I am only delayed sending an item at the moment due to a buyer paying by echeque. Ebay notifies me once cleared then I have to send the item but not before.
Some sellers can be slow. I was waiting for ages on one item myself. Even when they marked despatch it didn't arrive and I doubted it was sent in the first place and one of their reviews remarked on slow despatch/delivery.
I would chase up your seller and check their reviews. It could even be that they have sent it via the post office and forgotten to click the despatch button.
I am sure you can rate on delivery when you post your review, but give them a chance to respond to you first in case they have a valid reason.

I would send a question to ask... they may have dispatched but not marked it as dispatched, too.

Ebay makes sellers set a dispatch time, we are supposed to stick to that (you will be asked when you give feedback if seller met the target).

However, Your fault if you didn't read the dispatch time before purchase.

There have been times when I have forgotten to mark as dispatched and not realised until the buyer leaves feedback for quick posting.

There have also been times when I have bought something and the seller has genuinely been in hospital and unable to post.

Check the dispatch time on the listing, and ask the seller. You should check the dispatch time anyway before purchasing if you are in a hurry and not blame the seller for posting in the right time frame.

Mine is set to 1-2 days after payment, I received a payment this afternoon for an item, so will post Friday, I post on wednesdays and Fridays.