Truning the Valves when the pump is on

[RENOPOOL]

Hi
I just had my pool started up for the first time yeaterday. I thought when I brush the Dimond Brite towards the main drain I would see the main drain suck the dust/dirt right up. I called my pool builder and he told me to get more suction at the mail drain is to turn the valve that is set on half way between the main drain and the skimmer to all the way to the main drain. He told me to do this slowly because the pump is on. Everything I read tell me never to turn the valves when the pump is running. My pool builder does not want me to turn the pump off until next week. (Run the pump 24/7 for a week) Will I hurt anything? The pool does clear up in a few hours after brushing so I know the suction does work.
Please advise.