Is it a problem having veneers at the age of 23?

Hi:The main disadvantage of getting veneers at a young age is that you need to redo your veneers at some point again in your life time.  However, you can get veneers on both your upper and lower teeth.Best,Dr. Maddahi

dental veneer is possible at 23. but its my request to upload yr picture , so i can guide you better. if issue is with shape of the teeth then veneer is good option. there is no disadvantage with veneers, but little care is important for best aesthetic. veneers are possible in any jaw on any tooth. 

Getting porcelain veneers at a young age can make all the difference in one's life, especially thru the difficult teen years! Some of the youngest patients we’ve treated were around 15-16 years of age.
There a couple of factors to consider when getting porcelain veneers, especially when younger. First, your permanent teeth need to be fully erupted and in their final position. This usually occurs in your mid teens. Also, getting porcelain veneers is a non-reversible procedure, so make sure you are getting them for the right reasons.
If your teeth are slightly crooked, I would encourage you to consult with an orthodontist as well. Many minor issues can be corrected with Invisalign and some teeth whitening.
Assuming that your teeth are straight, and you just have unattractive teeth, then veneers would be a great option. Porcelain veneers are thin shells of porcelain that are permanently bonded to the front of your teeth. We generally place veneers on both the upper and lower front teeth. They are used to fix many cosmetic issues including: straightening crooked teeth, whitening discolored and repairing damaged teeth. Hand made in a laboratory, veneers are placed in 2 visits, and can last decades when properly cared for.
So for your situation, 23 is a good age for getting veneers. Some advantages are they can fix your one tooth that’s in front of the other one, and you can permanently whiten your smile! Unlike natural teeth, veneers will not discolor over time. Some disadvantages is the cost, and need to replace them at least once or possibly twice in your life.
Definitely consult with an expert cosmetic dentist who specializes in veneers! 

There are a lot of big reasons to use veneers and they can accomplish about anything you want in your smile, but they do lock you into having a restoration on the tooth for the rest of your life and at 23, you may well have 100 years ahead of you!
If the shape of each tooth is ok and it is a position issue, something like braces or clear aligners(like invisalign) may be better.  It will take a little longer, but is cheaper and you still have your own teeth at the end.  Sometimes a conversation with the dentist reveals that some simple reshaping is all it would take to get the tooth shapes you want.
On the other hand, sometimes the only way to really dial in your smile is veneers, and yes, those can be placed on the top as well as bottom teeth.  The best way to sort out what you want to correct is to take some photos and video of yourself smiling huge and talking... and look at the teeth you see.  Then figure out what you don't like about them and count up the ones you want to change.
Typically the front 6 as a set looks wrong and either 4 or 8 would make the smile look much better when you are done...
Hope that helps - and congratulations on your soon to be new smile!

It is difficult to evaluate your case with no photos. Veneers can be done on upper and lower teeth, but if they are done early in life they will probably need to be replaced at some point over your lifetime.