Отправлять благодарность за подарок до получения? Советы!

Wwyd...

So I'm not having a baby shower anymore. (My mil was basically planning it for herself and covid rates were getting crazy when we started to plan)... anyways I had already made a registry so people have started sending me things as I get closer to my due date. I have a babylist registry so I get alerts when people purchase things for me..

So do I wait to send a thank you note once I receive the item or can I just put it in the mail now?