Allowing sales while “out of stock”

I invented a product that I am currently having manufactured overseas. Soon I will need to determine how many units I want for the first order. Ideally sales would start slow and grow in a predictable way, but I am concerned about the scenario where demand is higher than expected. If I sell out of all my units quickly, it will take about 6 weeks to get a second order.

The last thing I would want is to lose momentum by halting sales altogether, but I also hate the idea of allowing sales to continue while out of stock. Even if I make it abundantly clear that items are backlogged and delivery may take 6 - 8 weeks, I still feel like people would be upset, or fail to read the disclaimer altogether.

Looking for thoughts and opinions on this situation.

Thanks!