You want to avoid over-boiling to avoid excessive evaporation which will make it more concentrated than intended.

Boil one minute. Thanks for asking, and for using the correct ratio. Be sure to keep the feeder free of mold, but don't use bleach. Use a bottle brush and then a small brush for the holes, maybe soak in white vinegar if it's real bad.
I'm not assuming that you don't know this, just sharing general info.

Add boiling water to the sugar. Makes better blend and no risk of too much heat burning the sugar.

Of impurities and the chlorine we use to protect ourselves.

They recommend a good boil of 1-2 minutes.

You're using the correct ratio. Stronger ratios dehydrate the birds.

Thanks for helping our flying jeweled friends.

so you'll see more activity than usual at your feeders! I never get tired watching them.