Windbreak tree spacing advice?

Looking for advice on how far apart to plant my trees for a windbreak.  I've going to follow this principle that I found (see attached image).  I'm starting with 8' spruce and 10' aspen.  How much space would you put in between the spruces?  Aspens?  In between 2 rows?  I"m in zone 3 so somewhat slower growing than a lot of places.  

Howdy Alison, If the spruce survive and grow they will completely fill a space 20 ft in diameter or more, so I would plant them on 20 ft centers. Aspen will fill in every space that you leave them so if I were doing it I would plant them about 20 feet apart and 10 feet downwind of the spruce. Will you be adding anything to the soil and or irrigating the trees?

Thank you!!  Yes, I will be watering them.  I was planning to apply this MYCORRHIZAE to the roots at planting time:  https://www.usemyke.com/en-us/products/natural-growth-enhancers/myke-trees-and-shrubs/
Not sure on amendments.  I'm currently waiting on soil test results.  But it seems like pretty loamy fertile soil.  It was originally farmland but has been fallow for about 40 years.  Lots of voles and ground squirrels around that seem to do a great job aerating the soil.  Although that makes me a little worried about the root balls getting munched.  Thoughts?