Powerhead placement

[StartingInUtah]

I am wondering if someone can answer a couple questions before I put fish into my tank (hopefully this weekend). My water parameters seem to be testing out okay but I am going to have the guy at my local fish store test it and give me the numbers (he will do it for free) so that I have a second opinion before putting any fish in there. I did not have a powerhead in my aquarium for my cycling process and hopefully that does not mess things up. I have them in there now (as of the last couple days) but have no idea how to tell where to place them so for now they are just creating some flow. This brings up two questions for me.

First, should the powerheads have been in there during the cycling process and if so what adverse effects could that have caused to not have them in there?

Second, how do I figure out the best placement of my powerheads?

Thank you for any help you can give me.

[Mr tap water]

Hi there
Having your power heads in while cycling your tank should not cause any problems the only positive I can see by having them on is help with the mixture of the water and to help provide oxygen if they're breaking the surface , as for placement of your powerheads by placing one Either side of your tank at about 6 to 8 inches down and try aiming them at each other and towards the middle of the surface, the idea is not to have no dead spots in the tank and some times can depend on your rock formation and can be down to just experimenting until you find the perfect spot

[Mr tap water]

The perfect spot .continue from above