Anandakanda 1.8.6

1.8.6

yathoktakāle siddhiḥ syātkumārasya rasāyanāt /
tasmāddviguṇakālena yūnaḥ siddhirbhaveddhruvam //

In the case of a young man, success from rejuvenation therapy occurs in the prescribed time; / in twice that time, success is certain for a mature adult;