Children are never too young to be brought to Church for services. The sooner we introduce them to the Church, her services, and her wisdom, the sooner we begin the process of "becoming" an Orthodox Christian. In order for Orthodoxy to make sense, our children need to experience all that the Church offers.
Make it part of this year's Lenten commitment to attend more services, or attend more often. When Holy Week comes, block out all other activities. Make it a point to attend every service you can with your children. Be creative so that you can keep little ones directed and occupied. Locate service books for children who can read. Explain what's going to happen. Talk about what Holy Week and Pascha were like when you were growing up.
The following article is taken from the Orthodox Family Life Archives:
Ways to Share Great Lent and Pascha with Your Child
by Ann Marie Gidus-Mercera
Take your child to Church!
Whenever a service is scheduled, plan to attend. Services like The Canon of St. Andrew of Crete may be physically tiring with the many prostrations, but don't think your child can't be a part of them. In my own parish, which is filled with pre-schoolers, the children do a great job of making prostrations right along with the adults. Many of the children will join in as "Have mercy on me, O God, have mercy on me" is sung. This experience is good for our children! If they see their parents attending services, they get the message that attending Church is important. If we bring our children to Church with us (both young and old), they get the message that their presence in Church is important. The Canon of St. Andrew of Crete is especially good for teaching our children that we worship with our entire bodies.