The fact that he says it was late clearly demonstrates that there was some kind of promised completion date, otherwise it wouldn't be late. And as I mentioned before, how long it was supposed to take isn't really important anyway. What is important is how long past the due date it is, although how late it is compared to how long it was supposed to take does make a small difference (like eight months late when it was promised for ten years is not quite as bad as eight months late when it was promised for one year although neither are acceptable).
All that being said, I just went back and reread the first post and there is a little ambiguity there. The way I first read it, and the way it still sounds like it probably means, is that it is eight months past the due date. But there is a chance that what he was trying to say was that it was late and past due date and finally after eight months from the order date is when he got fed up and wanted the refund. Like an example of that would be that the cue was promised to be delivered in four months, and it wasn't and then he got nothing but excuses for another four months before he finally got fed up. It that case it was eight months after the order date, but only four months late.
Like I said I think he meant eight months late, and either way it probably doesn't matter. Once you are real late the buyer is entitled to a full refund. It would be nice if the OP would come back and clear up the confusion though and tell us for sure how late it actually was, and maybe how long it was supposed to take since that might make a tiny bit of difference.
As for a restocking fee, you have to have taken delivery of the item and then returned it for it to need to be restocked. The buyer never even got his item (which is the whole problem) much less returned it. There is nothing to restock. Also the reason for the return has to be the buyers fault and cannot be the sellers fault. Like maybe you ordered a shirt from online and when it came it didn't fit, or you just changed your mind. Well that isn't the seller's fault so there might be a restocking fee. But say you ordered the shirt in blue but they sent a red one so you return it. Well that isn't the buyer's fault, he didn't get what he paid for, so no restocking fee. Or what if they never did send your blue shirt and after months of waiting for it you finally tell them to just forget it, you don't want it any more. Should you pay a restocking fee on the blue shirt they never did send? Of course not. And here the buyer didn't get X cue by Y date that he paid for either and it wasn't his fault, it was the seller's fault. No restocking fee.