If you can get a friend to arrange a baby shower for you or if someone offers to do it, the invitations should be sent out a month or two before the birth day, so that the mother is not in too much discomfort and is not likely to drop the baby during the party.
It is good to have handmade baby shower invitations
If you have the invitations printed to a standard size, you can purchase cheap envelopes at a budget stationery office, but if you go for some weird size, ask the printer to provide the envelopes too.
Standard details like the date, the time, the venue, your name and the baby's name can all be printed but you will have to write or type the recipient's name in personally. Add your phone number too so that people can ask questions if they have any. If you would like the party (and the presents) to have a theme, you should say that on the invitation. Perhaps the card could be in the same theme too.
In fact, if you want to go down that route, you could download a fitting image off the Internet, say, a scene from Peter Rabbit, and give that to the printer so that they can print that onto your card.
People are very busy nowadays, so make sure you give your friends at least a month to book you in and get a suitable gift for the shower. If you would like to be pretty sure how many guests are coming, enclose a stamped, self-addressed postcard in with the invitation, so that they can let you know easily.
If you are looking for baby shower games