First All Grain brew turned out a much higher gravity than intended...What now?

So I tried doing this recipe:

https://www.homebrewtalk.com/f71/ole-zion-church-saison-246288/

I adjusted it in BeerSmith with 65% efficiency since it was my first all grain brew. The pre-boil gravity was right on target with what BeerSmith Said (1.051), but my final gravity is reading 1.088, which is a full point higher then the recipe (1.078) and is significantly higher than what BeerSmith says (1.064)

NOTES:
-I couldn't put the 1 lb Candy Sugar in BeerSmith since it isn't in the program (or I at least couldn't find it).
-I used more grains then the original recipe since I assumed I would only hit about 65% efficiency.

I have been doing a little research, and it sounds like a beer with such a high gravity will take months to become drinkable (though the original recipe said around a month and a half to two months). It also sounds like I may have not pitched enough yeast for such a high gravity. I used one Wyeast 3711 French Saison smackpack.

I guess I want to know why I got such a high post-boil gravity reading and how I should handle it. Also, what should I expect in regards to how it will change the characteristics of the beer (ie ABV).

Any help would be greatly appreciated!

RDWHAHB. Give it the recommended time. Or don't. It will be fine. Don't stress about the yeast it well be fine too.

For future reference, if your starting OG is higher than expected, you can use beersmith to calculate how much water to add to dilute the wort to the proper SG.

It sounds like you need a few batches to find your average brewhouse efficiency. It also seems your boiloff rate is incorrect in beersmith. Once you measure those, the all grain process becomes much more predictable. In order to measure boiloff and efficiency, you really need to take special care to record consistent and accurate measurements of volume, SG, time, and temperature. After that, dialing the recipe into beersmith can yield you very accurate predictions, although there are always variables keeping the predictions from 100% accuracy.

For the batch you just finished, hopefully you oxygenated your wort enough to have a healthy growth phase. Keep tight control of the temperatures and ramp up a few degrees at the end to help your yeast finish the job.

sounds like your 65% efficiency was about right. you increased your FG by adding a lb of sugar that it does not sound like you accounted for in BS. It also sounds like you boiled off more than you anticipated in BS.
Take great notes for the first 5 to 10 all-grain sessions like JW points out above. make a spreadsheet and record everything. slowly make adjustments to your process until you get your system wired.
As they say, "don't sweat the petty...", your beer will turn out just fine. give it 4 or 5 weeks in primary and a couple more to carb up and you will have beer to drink.

You could finish it as is, or add a bit of water to adjust the gravity down. Look for an online calculator to know how much.