If there is only one delivery address on your order, all your items will usually be dispatched on the same day.
However, if some of your items are dispatched from different warehouses, or require additional processing time (i.e. for personalised items), they may arrive on different dates - but still within the quoted delivery time frame.
This will mean different shipments with different tracking numbers, and they will be processed by local Customs separately.
We state in all our dispatch emails "Please note that some of your items may be delivered separately. In such cases, we will always send you a separate tracking email for each delivery."