Yes and No, Both. This can very well be your first trek however the answer to this question boils down to how prepared you are both mentally and physically. I also strongly believe that some kind of trekking experience is of great help here as it shows you your true stamina, ability to survive in harsh conditions and how much you can take in and till when.
Consider this. If your body is fit and ready to cover 15-18 kms per day and tolerate temperatures as cold as -35 degrees then Chadar trek can be your first trek.