first time dried starter question

New "ish" baker, new to forum!  I started to revive a dried starter a few days ago. Fed it this morning as per the schedule, and within 1, ONE HOUR, the starter has doubled to over twice the volume. This is day 2 or 3 of twice daily feeds per directions.  My question, is this normal, and is the starter now ready to use?  I can hardly stand it!!!