This will depend on the current status of a trainee's Portfolio and how their individual Deanery Admin Team chooses to administrate their training.
Deanery Admin Teams
Some Deanery Admin Teams will create a trainee timeline where they create Review Periods for the trainee in advance.
The trainee will need to have the correct Review Period listed as their 'current' Review Period and then when the ESR is signed off, they can choose the correct Review Period to move on to.
Usually, when an ESR is signed off the Educational Supervisor has the ability to create a new Review Period for the trainee to start working on straight away.
If an ESR has recently been signed off and the Educational Supervisor has not created a new Review Period, and the Deanery Admin Team do not create these in advance, then the Trainee will be able to create themselves a new Review Period.