God's time is the best., Is that true?

I was reading some religious notes that i jotted down in my church sermon's note when I saw a quotation where God told Abraham "...at the time appointed i will return unto thee according to the time of life, and Sarah shall bear a son." This set me thinking, does that mean that God work with man in accordance with 60 seconds make one minute,60mims make 0ne hour, 24hour make one day? Because my understanding of that scripture is that God follows man timing in answering man's requests. Anyone there with a different view, kindly counter my theory.