You're right about the edges and the circle. The center faceoff circle does line up within the square formed by those hockey dots. Our faceoff dot is hard to see - it's blurry and almost the same color as the critter "chewing" on it, lol. I assume Preliminary will be double-paneled, so each skater gets half-ice, so I never thought about teaching it from the center. The end circles were a disaster - they just followed them to the edge of the rink, which was fine for the crossovers, but too big for the circle patterns. I'll give your place a try; I like to keep my kids challenged and ready to deal with any last-minute adjustments.
I teach this pattern with a blue hockey line as the figure's axis. It gives the skater a visual diameter and an easy-to-spot center once they've marked it on the line. I find it easier to see whether it's really properly shaped. (Says the queen of the egg figures!)
Unless the skater has unusually short or long arms, I've found that they can "spot" the edges of circle patterns when they indicate their axis. Standing on center, shoulders over hips, they raise their arms to around shoulder height and look down their arms. The horizon point where their fingers seem to "touch" the ice is usually the "3 times their height" outer circle edge. Since their arms are proportionate to their body, it works pretty much every time I've checked the measurement. It helps the skater look ahead to the next part of their circle.