according to race notes, it should after the pit lane exit lights and in the pit exit only
there is no specifics according to the pdf https://www.fia.com/sites/default/files ... on%203.pdf
19) Practice starts
19.1 Practice starts may only be carried out on the right-hand side after the pit exit lights and, for the
avoidance of doubt, this includes any time the pit exit is open for the race.
Drivers must leave adequate room on their left for another driver to pass.
19.2 For reasons of safety and sporting equity, cars may not stop in the fast lane at any time the pit exit
is open without a justifiable reason (a practice start is not considered a justifiable reason).
This picture u can see the pit exit in this track is very long, so they can do it anywhere. they just have to pull to the right and not to impede others.
They just say right-hand side after the pit exit lights...so technically Lewis can do it until the safety car lane (which is the end of pit exit)