Of 12 new sites scheduled to open in 2016, seven are in the capital, including Aldgate, Tooting and Peckham.
The company floated in November at 195p. Its shares were unchanged at 230p.
Analysts at Numis said: “We are holding our forecasts, which anticipate the company tripling its EBITDA over the next four years, and are upgrading our target price to 265p from 250p.
“Following recent strength, our recommendation moves to Add from Buy.”