I asked Zero1 about delivery date and notice. Here is their reply:
Hi xxx,
Thanks for your interest in Zero1!
Before your delivery is dispatched on the selected day, you will receive a confirmation email/SMS regarding your delivery details. Please reschedule at this point if need be. Should the delivery attempt fail due to missed delivery slots or verification failure, Zero1 will notify you the status via email/SMS/phone call. The customer will be liable to pay S$10.70 delivery charge for the second or subsequent delivery attempt. If an additional delivery attempt request is due to a delivery failure on Zero1’s part, we may waive this S$10.70 re-delivery fee upon investigation and at our own discretion.
Should you require further assistance, please do not hesitate to contact us again.