In my previous church in East Asia, we did not have a nursery or "cry room" for children because not only the little ones of Israel attended public reading of the law; as well, we could not find any scriptural warrant for separating the children, and we all agreed that the regulative principle applied.
I believe the Holy Spirit blesses our attempts to teach our covenant children to learn to be still during the worship service. As soon as our son was old enough to respond to discipline, we prayerfully & proverbially blush taught him to not throw tantrums at that time. It worked.

In this was manifested the love of God toward us, because that God sent his only begotten Son into the world, that we might live through him.