That is the case yes MC was "missing" for a bit in the present and your family/darci freaked out about it the same thing happened the second time he went but it was done quickly enough that nobody noticed he was "missing". Regardless of Skylar spending time in the past or being from the future she proves there is more time travel than the "go back exactly 20 years" that MC has done.I'm more curious about if with Skylar's trip to the past if somehow how much times passes between future / past got changed. As from what I recall the first time the MC went to the past and came back to the present the same amount of time went by. Skylar would need more than a week in the past for 2 sets of sleeves to heal unless that is future Skylar maybe.
Skylar's tattoos are unironically the smoking gun that will solve time travel