We analyse the implications of order timing decisions in multi-retailer supply systems in a single period, newsvendor setting. Specifically, we investigate a supply chain with multiple retailers and a single supplier where one of the retailers is considered a preferred or primary customer of the supplier. In the base model (delayed commitment), customers order after observing demand and the supplier rations its production quantity to retailers according to a generalised uniform allocation rule. In the early-commitment model, the primary retailer commits to an order quantity prior to the selling season and receives her order in full. We compare the expected supplier and retailer profits under each of these strategies and specify conditions under which a particular commitment scheme benefits the supplier, the primary retailer, and the entire system. Our findings indicate that the supplier prefers early commitment under mild conditions, whereas the primary retailer's preference depends on the tradeoff between the supply risk and demand risk. We also compare our findings with a single-retailer system, and observe that both the supplier and the primary retailer benefit from the existence of additional customers under delayed-commitment in many contexts.