Thank You Note Ettiquette

I'll be honest  - I just do not remember what I did with regard to my wedding shower - and I'd love your help.

My baby shower is not until the end of March, but the host sent the invitations this past week. A few of my guests have sent the gifts directly to me -- two from new moms who told me that they wished they had more time to get things assembled before the baby's arrival, and a few are friends/family members who cannot make the event but wanted to send a gift.

So, this brings me to my question -

For those unable to attend the shower, who have sent a gift. I plan on sending a Thank You immediately upon receipt of a gift.

For those who are attending, but chose to send a gift in advance - do I send a Thank You now? or do I wait until after the event and thank them for both their generous gift, and for attending the shower? I will plan to also acknowledge them at the shower after opening gifts so all the guests know that they gave a gift - but sent it to my home.

Appreciate the help in advance. I usually know my ettiquette but in the third tri my brain has become spaghetti.