I would argue we already are contenders. The combination of players, coach, system, back office...it's all working and it's pretty clear the league is taking note (see Kerr's latest comments).
Yes it is still early in the season (with only 18% of games played) but we have played 6 games against difficult teams (CLE, MIL-2, SAS, TOR, OKC) and stand at 4-2 in those games. When we have a greater sample size (10-15 games) against truly contending teams, then we can use empirical data to support the claim. Which will happen by mid-January. Games to watch:
GSW (11/16)
MIL (12/4)
SAS (12/8)
MEM (12/16)
WAS (12/25)
HOU (12/28)
CLE (1/3)
Honorable Mention
DET (11/27 & 12/10)
PHI (11/30)
MIN (1/5)
NYK (12/21: this is a different team now)
So by January 15th, we'll have an ability to really point towards our ability to not only compete but win a championship. It will give other teams we've beaten a 2nd chance to contest CBS system differently and we will see what this team is made of against switches.