From 28 weeks
Once you have had ‘limited capability for work’ for 28 weeks, you can claim HB to help with your rent (if you can make a new claim for this - see
here).
The 28-week period runs from the day your limited capability for work begins, not from the day you leave your course. See
here for how limited capability for work is assessed. You do not need to have been working to count as having limited capability for work.
Note: you can have limited capability for work but still be able to study, so HB can continue when you return to college or university.
Example
Sean is ill and takes time out of his course. He is not eligible for PIP, and has not worked enough to qualify for contributory ESA. He gets no benefits until he has been ill for 28 weeks, when he can claim HB (because he lives in temporary accommodation). He makes a claim for ESA, supported by a backdated medical certificate, in order to establish his limited capability for work, and also fills in a claim form for HB.