I commend you for your efforts. Separating yourself from those of Titus 1:16 that publically say they know God, but disown Him by their works.
It says you want to worship "in deed and truth." (1John 3:18)
First, I would say to be honest with your kids. Don't say there is an Easter Bunny or Santa Claus. You want them to have presents, great! Don't claim they are from fake person. Admit you bought them because you love your kids.
At some point in the future, they will discover how truthful their parents were and how important that is. Trust is important all throughout their lives.
Too, you can show them from the Bible, it is always the right time for this, that Christ's death, not resurrection is the only anniversary we are supposed to keep. (1Cor. 11:20-26) Notice "keep doing this in remembrance of me." He never said this about any other occasion; birth, baptism, resurrection, etc.