Normally, the water chemistry between your two tanks won't be much different since you've filled them with the same tap water. So switching fish between two tanks like that is not that stressfull. I personally just net the fish out of one tank and drop it into my other, recently did it with 3 new ottos and a platy. The Ph and temperature reads the same on both tanks and I don't see what elese could have changed the chemistry of my tanks considerably to actually cause any stress to the fish this way. The fish just kept going like they were in the same place. Acclimation via bags and adding water and keeping fish in buckets, netting 3 times is a lot more stressfull if it's not necessary, which in your case, as long as temperature wise the tanks are close(within 1 degree) and the Ph the same, just pop them in the other tank once cycled. This will cause little to no stress. If you can even scoop with water instead of netting, then the stress is very minimal
What I am trying to say is that as long as you have one of the tanks cycled, it's better to move the fish than subject them to even the minimum ammount of ammonia or nitrItes. You can never safely do a fish-in cycle.