For the de minimus rule there'll be an option of $100 or 120% of the goods' declared value, going up to $200 in June. It's unlikely that customs will check the actual value of the goods so I imagine there'll be a lot of under-declarations. Those are for items shipped via the postal service. For other services, goods shipped will be subject to the regular 145% tariff.
What this probably means is that if your order of spinners arrives in the US after May 2nd, then you'll be informed about paying 120% tariffs before the package will be released. I don't know how much your seller declared them for, so the declared value could be whatever you paid for it or a lot less. If you don't pay the tariffs, the package will be auctioned off.