I'd agree with most of the previous thoughts. Spring is a great time to plant, but fall can work too in some places. Go ahead and plant outside your original area if that is better. Regardless of the spots you pick, be sure to dig generous sized holes for the trees, the old saying is dig a $10 hole for a $5 tree. Be cautious about mixing anything into the planting hole soil. Most sources say now a days that you should use only
native soil in the hole and put your amendments on top after you fill it (just be sure not to put mulch, etc too close to the trunk, say 6+" away). Do take the lay of your
land into account, not only the sun but drainage too. If any of your tree spots are prone to flooding, you probably want to plant your tree into a mound to raise it above the surrounding ground level and/or be sure the tree/root stock can handle occasional ground flooding.
I'd also do some research about what root stock varieties you want on your trees. Many people just think about size (dwarf, full, etc), but there is more to root stock selection. Some are known to be better for certain soil types (clay, sand, etc), others have resistance to diseases and/or insects, other are good in cold places, etc. Do a little checking with locals (maybe even your coop extension) about what root stocks they recommend in your area for the different trees you want. And then of course, buy your trees from a place that will tell you the root stock they are using; some do some don't.
And of course, do some research about what varieties of the various fruits you want you should plant, if you haven't yet. Not every
apple or pear or whatever can grow everywhere. You need to be sure that your growing season is long enough for the varieties you choose to ripen most years. And for some fruits, you need to be sure your site has enough winter chill hours for the tree to "think" it has gone thru a winter. You might also want to check out how your chosen varieties do in terms of diseases and what diseases are common in your area. For example if fire blight is a common disease in your area you want to choose fire blight resistant varieties. And that the variety can handle your minimum winter temps.
It may seem like a lot to check out and research, but a fruit tree is a long term
project. Better to spend some time up front rather than be badly surprised in the future when your tree dies of a common disease or you find the fruit can't ripen where you are, etc, etc. And there are several fruit tree growing forum on the web where you can get tons of info.
BTW - sometimes the big box stores have great fruit tree, good varieties on named root stocks, in good condition. Sometimes they have junk. You really can't make a broad judgement it varies year to year and store to store.