Eight weeks after your first rent is reported this will be available on your free Experian statutory report under the "Rental information" section as seen below.
For Equifax this will follow the same process. You can access your free Equifax Statutory Report here. Example below.
Further payments will then appear monthly thereafter. What is important is this is the report that the lender sees.
If you did ever have an issue seeing the rent on your report you must contact them using these forms:
Experian - https://ins.experian.co.uk/contact
Equifax - https://help.equifax.co.uk/EquifaxOnlineHelp/s/
They will then help resolve any issues.
CreditLadder believes it is important to begin reporting your rent payment history as soon as possible to ensure your credit history is as strong as possible.