I like the idea of having a queue. But at that point what makes me different from a vote bidding bot?
I started UpvoteWhale because I saw a distinct lack of instant upvote bots. If I were to setup a queue type system then it wouldn't be instant upvotes anymore.

I believe most people use my service because it's an instant upvote so they can take advantage of the added curation rewards from having the post upvotes within 30 minutes of posting.
If I were to remove the instant aspect of my bot I believe that diminishes its worth.

I do however have plans in the future for having the refund explain the estimated time before upvotes are enabled again. Of course, this will be a much later update. The current list of future updates I believe has priority over this feature.