Haven't used instacart so can't comment on that, but have used Dizzy dolphin, excellent service. I found it really easy to use, prices reasonable and they will get what you want from where you want and I amended the order a couple of times before finalising a couple of days before we went, you can also pay with paypal.
I haven't used Dizzy Dolphin but it sounds like Instacart is a little different. Like its name implies, they try to fill their cart as close to the instant that you place your order as possible. Delivery is typically scheduled for the next day, or as soon as 2 hours after you order.
Dreams Unlimited Travel is committed to providing you with the very best vacation planning experience possible. Our Vacation Planners are experts and will share their honest advice to help you have a magical vacation.