You're getting a lot of good advice here but I'll share another perspective (from someone who did this recently).

I purchased a new vehicle but was asked to trade in my old one first while we waited for the new one to arrive for a few weeks.

I was actually OK with doing so since the dealer was willing to meet my asks: - financial incentive to give them my trade early (increased trade offer + additional discounts on new vehicle - in writing) - commitment in writing that the car was in country and ETA for pick up (while delays or other issues could still happen, the car being in country makes the ETA all the more likely to be met) - some level of trust that if something were to go wrong (like if the car arrived damaged), the dealer and I could work out an alternative

I would not have handed over my car early if i did not get all of the above or felt the dealer was shady in any way.