I don't know too much about spruces, but here is a link to Harry Harrington's species guide
http://bonsai4me.com/SpeciesGuide/Picea.html
I wouldn't recommend putting your tree in the ground until you have checked the roots. What you are looking to see is if the roots have colonized the pot completely or not, or if the tree rootbound. On a day close to planting time (not now or you could risk root damage) when the soil is on the dry side, gently lift the tree from its pot. If it takes more than a gently pull, you can guarantee the plant is rootbound so leave it until you're ready to transplant. If the plant comes out of the pot, is the rootball intact (meaning all of the soil comes out of the pot with the roots)? You should see the white tips of the roots on the outside of the rootball. If the rootball is not intact (meaning 1/4 to 1/2 of the soil remains in the pot), look for possible root or soil problems: slimy soil or roots, foul smelling soil, significant difference in soil texture or moisture between rooted and non-rooted portions, bugs, etc. If there are no apparent problems, put the non-intact plant back in the pot until next fall since it still has room to grow in the pot. Transplant if rootbound or intact when weather permits. As far as planting is on a tile, I don't know if it's necessary or beneficial with this species, but I will share an observation I made concerning planting conifers on a tile.
About 10 years ago, I was planting several shimpaku junipers on tiles in the ground. I picked up some old plates at the Goodwill that I thought would work great (and they did the job). But I was lacking 2 plates, so I decided to use some hardi-plank (cement siding) we had left over. [Let me preface this with our particular environmental condition: We have very acidic soil (tests ranged from 5.0 to 5.8) because the soil is extremely eroded and contains lots of iron.] The junipers growing on the cement board easily outgrew the others, and they were a deeper green and generally more healthy. Conifers, in general, like neutral to alkaline soil, and obviously the lime in the cement neutralized the acidic soil, giving the junipers more ideal growing conditions. So, if you have acidic soil, I would highly recommend using cement board as a planting tile for conifers.