eight o'clock
Twenty more brought pennies . By this time there was a stern look on the principal 's white face . During the next few minutes after that only two or three came in , for Dick had thought of a new aspect to the joke . He had sent messengers scurrying out through the street approaches with this message : `` We 're not required to be in the assembly room until eight o'clock . Let 's all wait until two minutes of eight -- then go in a throng . '' So the principal had a chance to catch up with his counting as the minutes passed . So busy was he , however , that it did n't quite occur to him to wonder why so few of the student body had as yet come in .