Panchmasiyoo is done in the fifth month, any day is good. Basically, both sides parents do sagan (like we do on birthdays) to both the parents to be. It is generally done at one place, where the families meet to celebrate the coming of the child. Nothing is done for the coming child yet, but you may give gift to the couple.
Best wishes always, enjoy the day.
Thrity Tantra
Panchmasiyu Pachmasiyu,