Cristina,
I would recommend against placing that you will send xyz version in 24 hours in your listings. Here is why.
1. You would be committed to shipping a custom item that the customer probably does not want and will be unhappy already setting a negative tone.
2. When they either give you bad feedback for shipping the wrong item or contact you to tell you its not what they want you will have to replace it and reship.
3. Sending the wrong item...you are out postage both ways, an item that you can not just turn around and sell.
4. Even saying that it was written, the customer will say they did not see it or misunderstood that. Paypal and Etsy are going to stand behind the customer as they should.
If it is possible, Annabels idea for variations in the listings is a great idea. We use those in some situations. However, the customer does not always use them.
We have had customers do an MIA on us a few times. We are patient and send out emails to both Convo and regular email. 1. to CYA 2. to notify customer that
We are ready to start their order, but need ____ information to begin. Please contact us as soon as possible, so we can finish and ship your _______.
Its been awhile and we have not heard from you. Please contact us with the needed information. We are excited to get you your order but can't start without _________.
Copy and paste and send out at least once per week. The customer will eventually get in touch with you =)
Any questions, contact me