Excellent, so I'll leave it alone for now, repot in spring, wait for the lower branches to get thicker, and then chop the trunk.
What about keeping it short by pinching the apex and just letting the trunk thicken on it's own? Will that get me there or will I still need trunk chops to get taper in the end?
Yes, no more pruning, do repot in spring. Then let it grow to recover from the repotting for the entire summer. Look for an appropriate training pot now, to repot it into in spring. The training pot should be less than 5 inches (12.5 cm) in depth, 4 inches (10 cm) is more ideal depth for training. It should be wide enough to hold roughly the same nearly the same volume of potting media that the current pot holds. You will have to be pretty aggressive to comb out the roots, remove the downward roots that would keep the tree sitting too high in the pot. When you are done, the potting media should be level, and at least 1/4 inch below the rim of the pot. If you have to mound the soil, you did not remove enough off the bottom of the root ball, take it out and remove more off the bottom. The training pot can be rectangular, or round, it is your choice. Wide and shallow. It can be a ''production grade'' bonsai pot, or it can be plastic, or a large bulb pan. It can also be a home made wooden box. What ever you want.
As to training by ''pinching'', this is not a ''good'' technique over the long run. There is a fine distinction between pinching and pruning, and some confusion as to when an action is one or the other. (I have no fingernails, so I pinch using a scissors) Someone who already is fairly experienced conceivably could develop a spruce only by pinching and pruning of newer (less than 3 years) foliage. BUT, in general at some point the top will have a tendency to thicken branches quicker than the bottom, and no amount of controlling foliage by ''pinching'' or pruning will ever keep that in balance over the long term. At some point, removal of the top portion of the tree, to be replaced by a younger branch will be necessary. But with the current plan you have of repotting in spring, allowing to recover without pruning over the summer, You have a number of months to read up on spruce as bonsai both here on BNut and on other websites and other articles. In general, bonsai techniques used for most species of spruce can be applied to Dwarf Alberta spruce. The DAS does have a few unique quirks, but otherwise it is a variety of Picea glauca, and as such most spruce techniques will work on DAS. So your assignment to complete by the end of summer is read up on spruce as bonsai.