11 And Clara Had More Time Together Than You Think.

11 and Clara had more time together than you think.

This is not an 11 vs 12 thing, I'm way past that.

In terms of episode number, Clara had 2 series with 12 compared to the half-series Clara had with 11. But there is this that I would love to mention that 11 and Clara, technically had 3 years together, from Clara's POV. and there's canonical evidence for this due to perhaps a mistake Moffat made by accidentally making a retcon he didn't know he was making.

Point 1: Clara's (Then) age.

In the Bells of Saint John, after laying Clara down in bed the Doctor was looking around and found upon Clara's 101 Places to See book which was given to her from her mother and had written down her age throughout the year, there is only two years missing and it was 16, maybe connected with implication of her grief to her mother, 23 is also missing but Clara may have forgotten to put it. But the latest was 24. Implying that Clara is 24 by the time of the Bells of Saint John. The episode taking place in 2013, which implies that Clara (before then) was younger than Jenna who was 26 at the time of filming (Fall of 2012).

Point 2: The Accidental Retcon.

In Deep Breath which takes place immediately after Time of the Doctor (Christmas 2013), Strax who was examining Clara mentions she was 27. Jenna's actual age during filming (January 2014) and with that, here it comes; Clara had spent 3 years of her life with the Eleventh Doctor. With this accidental retcon by Moffat which he forgot to address Clara's age as seen in Bell's with the marking down on her book by putting down Jenna's actual age.

Point 3: The Time between The Name and Day of the Doctor.

The Name of the Doctor, ended with the reveal of the War Doctor with the Doctor, carrying an unconscious Clara, out of his time stream. With this, the next episode/special: The Day of the Doctor. Clara was no longer working as a nanny from the previous series but now as a teacher in Coal Hill, a call and message sent her to where the Doctor was, after a bike ride and entering the TARDIS, both entailed a huge hug together and from the dialogue, which implied it has been months since the last time they travelled together. (presumably the Doctor giving her space to adjust her new job as a teacher.) It's likely that before Clara got to her job, both her and the Doctor had travels that lasted in her 25th and 26th years. Considering Clara was 27 in Time and Deep Breath, there may have been more travelling before Time of the Doctor took place.

Conclusion.

From the points I mentioned, the first time Clara met the 11th was when she was 24 and during then she had 3 years with him until he regenerated as the 12th by the time she was 27.