Great question! Don't an 8 foot in a 5 weight. But, do one in a 4 weight. Able to get 50 feet plus with a double haul cast,... even caught a fish while doing the demo! Fun stuff!

Fly Casting Demo... Redington Pursuit 8 ft 4wt! Casting 50 feet or so? #flyfishing

The OP stated that he received the setup as a package deal; there's a good chance that the rod is pretty soft. If that's the case, overlining would be a huge mistake. I realize that overlining is all the fad now; I have seen people post that they automatically overline every rod in their quiver. With all due respect, overlining is for fast rods, and not all fast rods (and definitely not all new casters) should overline. Indeed, overlining could greatly lengthen his learning curve. Let him learn the basics and go from there. I'm sure that he will receive many suggestions to overline, but that may be detrimental to his rod and to his casting education. Someone who is right there with him, watching him cast, and able to evaluate his skill and equipment, should be the person to determine whether overlining would be beneficial.

Agree. The speed with which some folks on this board leap to overlining as a solution to every problem with casting is perplexing.

To the OP -- 40 feet from your feet to the fly is more than enough for most 5 weight fishing.

Another convenient measure -- the head (heavier part of a weight forward fly line) of the line is usually marked by a color change, and is usually in the ballpark of 40 feet of fly line. If you can cast the whole head plus a leader that will be closer to 50 feet, and you're in good shape. But, don't fall into the trap of distance distance distance; accuracy is probably more important.

A new line will make a big difference. If you are going to fish in local lakes, I prefer an 8'6" or 9' rod for 6-8 weight line. But I catch carp, buffalo, hybrids, largemouth, and stripers. I have found that a fly rod is like a lot of other sports equipment and the best rod and line for one angler may be different for another. If you are after distance then keep the line clean and conditioned, but I agree with others that accuracy is more important. My last state record on a fly required a 10' cast.

most can get past the backing knot with proper technique and ideal conditions
your mileage may vary
realistically 40 - 50' is practical and as mentioned accuracy is the key -- which will come with lots of practice

You didn't post your location.
Somewhere nearby should be a club or a fly shop that offers some freebie lessons.
Failing that, get a video, keep a rod rigged up in your garage and work on what the video shows you 5-10 minutes a day.
Kill two birds with one stone, take some guide trips, most fly fishing guides can scoot you up the learning curve.

I remember reading somewhere that if you reach the point where you can cast all the fly line off your reel, you are in the top 5-10% of distance casters. To get there you will need the double haul, and that just takes practice. You will know when you have it figured out when you can feel the load you create on your rod tip pulling hard at the fly line you are holding while false casting and the entire casting motion just feels like it is in a good rhythm. Having said that, distance casting vs. shorter, accurate, subtle casts reminds me of the Mark Twain quote: "As a form of gratification, fornication is highly overrated relative to defecation."

I will warn you that the pursuit of distance without the benefit of good technique can really wreck your casting arm.. don't ask me how I know this....

I fish with a 20 year old 7 wt that I always struggled with distance . I ended up putting the next weight up line on and fixed my troubles . I only did this per a instructors advice since my particular rod wasn't " loading " quite right with 7 wt line .
People like instructors and guides can be a wealth of advice and knowledge .