The amount of paradox in this situation is endless:
Bob the customer clicks the purchase button for something that is bought off Amazon, choosing instant delivery.
Bob could changes his mind, cancel his order and go for a walk, encountering the delivery worker who just got out of his truck is one.
Bobby the delivery driver gets a thing saying 'deliver this thing to Bob at this time' on their delivery schedule.
Unless the delivery event info is stored locally on his device, it will not exist in the delivery database when he travels back in time. Also, this does not account for past Bob changing his mind and cancelling the order, also leading to problems.
Bobby drives to Bob's house, taking 1-2 days like normal shipping.
Wait, we've normalized time travel but not teleportation? Pretty sure we'd have teleportation or at least drone delivery perfected by now...
Bobby pulls up to Bob's house and pushes the time travel button.
This very action and all those following are now creating endless alternate theoretical futures. Bobby may accidentally scare Bob's cat, Roberta, by materializing into existence in front of her. She stops chasing the mouse she had been chasing which had accidentally ingested a diamond, and said mouse would have been a ritual gift to Bob, who, upon investigating, would have found the diamond inside, taken it as a sign that he can now propose to his girlfriend, now having a stone to set in a ring he added to his wish list but had decided against, and this delivery was the ring he had chosen instead. Bob's girlfriend, Gertie, instead of giving up on Bob because he's taken too long to commit, decides to marry him and start a family...and that is only one of an infinite list of alternate future universes for only one individual this action would affect, not to consider the ecological impacts if Bobby accidentally materializes on top of the last endangered Gypsy Moth, wiping the species out forever...
Bobby exits the truck with the package 5 minutes before Bob clicks buy.
Bob cancelled his order 4 and a half minutes ago, but Bobby doesn't know yet because the delivery order can't be updated from the past due to certificate errors with the delivery API due to time differences.
Bobby knocks on the door after Bob clicks buy and delivers the package to Bob.
Bobby has had 5 minutes to create more paradoxes and butterfly effects than any current supercomputer could track...
Bobby goes back to their truck and pushes the time travel button again, travelling to three seconds after they left.
If a random hit and run driver totals Bobby's truck, he's not getting back to the future any time soon, and by this time the universe has imploded because Bobby cannot exist in the past without changing the future. Any sustenance he takes will not be available for the individual it was 'destined for', leading to even more butterfly effects, not to mention any personal interactions he may have such as meeting someone new and causing new and complex relationships to both cease to exist or come into existence.
Bobby drives back to the Amazon warehouse for their next package or continues on their route.
Oblivious to the irreparable damage he has done to the present and future, Bobby continues on his way, never meeting his future wife, Gertie, because she never moved to San Francisco after deciding Bob had gotten cold feet and was never going to commit. The Gypsy Moth, having been mankind's last hope for cloning a new generation of species that depended on the moth's special genetic traits, is now gone, and in despair, one of (insert nuclear superpower here)'s top generals convinces one of his fellow generals to help wipe mankind out by initiating nuclear missile launches.