Muhammed PBUH had a number of common practices before Eid salat. He would begin the Eid takbeer from the evening before and softly chant it on foot as he went early to the masjid to offer his prayers on the day of celebration.
He would wake up early and have a complete bath, brush his teeth using his miswak, put on his best clothes and athr. He would commonly eat 3 dates before leaving, following one route and returning a different way so he could greet as many people as possible.
While you make this simple prayer mat, speak to your child about the takbeer of Eid, and how we should start our day. Discuss the direction of qibla from your home and why we pray towards the Kaaba.