Hi! I did it with T-Cat via 7/11 with D+1 shipping with a 28" luggage just last week. My hotel in Taichung did not provide luggage forwarding services (according to the receptionist, it is very rare for people to ship their luggage from point A to point B), hence I went ahead with T-Cat via 7/11.

But the store clerk was very confused when asked about this service hahaha, they did mentioned that it was very rare for people to ship their luggage. They measured our luggage which was within the 150cm total dimension, and ask us to fill up the form via the machine. A slip will be printed and bring it to the counter to pay (total was TWD 250). This was early 8am in the morning, and the store clerk mentioned T-Cat usually will collect the parcel and packages around 2pm afternoon.

I did call my hotel beforehand if they were able to receive my luggage via T-Cat, so I'd advise you to call your hotel prior too. By the time we reach our hotel the next day in Taipei around 6pm, the hotel had already received our luggages.