The question arises a lot, not just for employment status, but for other questions as well, like marital status.
There is no rule covering the situation, but there is a 'best practices' solution.... Put down the correct answer as of the application date. The application date is the date when you pay the fee.
Then go to Part 9 of the form (the 'Remarks' section) and include a brief statement that you expect your employment status to change during the life of the visa. As a template, you can use something like this...
Material change of circumstances: On (dd/mm/yyyy), my employment
status is expected to change from (xxxxx) to (yyyyy). This is because
If it changes to something else, or there is some other material change in your circumstances, you should contact them and let them know. This is covered in the undertaking you sign at the bottom of the form...
I must inform the UK diplomatic mission if there is a material change
to my circumstances, or any new information to my application becomes
There is no legal definition of 'material', the law only uses the word without defining it. The courts have applied a definition as any circumstance which would alter or affect the ECO's decision. Failure to comply with this definition is grounds for removal or a ban under Paragraph 321.