Sellers set their own shipping policies, so the delivery for your entire order is dependent on it.
If you strongly prefer receiving everything on the same day, it can be possible. Most products allow you to select a delivery date and time slot. All you have to do then is to choose the same delivery day and time for all products in your order during check out. In this way, you can get them on the same date.
However, we don't recommend having everything delivered on the same day because the shelf life and prep time of products differ. While you would certainly want to arrange for cakes, food and balloons to be delivered on the day of the party, you may want to receive party favours, disposable utensils, decos and props in advance instead. This is so that you have sufficient time to package the party tokens for your guests, set up the venue and arrange the props.