I would try to work some promo/marketing strategy/plan into it that would support the product delivery/release date X. Use that as part of the sell to promote the pre-book to buyers...and of course it would help the product too.
Hype it up with a release date, like music artists do with new records.
if you're going to take the pre-book approach, while you are there talking to the buyer, what has been done in the past is you take out a mag full page ad and inform the buyer their store name will be included in the ad where peeps can buy.
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the other side of the coin,
at this stage of the game it depends who your buyers are. A lot of them when they like what they see they may want to buy it right there and then and not wait for it.
So, it's always good to have ready made stock to sell and promote too.
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