From the notes of the section 8, 7A is always one month even if 14 is included.

As long as the tenancy has a term deeming service at the property is sufficient (as is the case in most agreements) then service at the property will be enough.

Where the landlord is seeking possession on ground 7A (with or without other grounds), court proceedings cannot begin earlier than 1 month from the date this notice is served on you and not before the date on which the tenancy (had it not been assured) could have been brought to an end by a notice to quit served at the same time as this notice. A notice seeking possession on ground 7A must be served on you within specified time periods which vary depending on which condition is relied upon:

Where the landlord proposes to rely on condition 1, 3 or 5: within 12 months of the conviction (or if the conviction is appealed: within 12 months of the conclusion of the appeal);
Where the landlord proposes to rely on condition 2: within 12 months of the court’s finding that the injunction has been breached (or if the finding is appealed: within 12 months of the conclusion of the appeal);
Where the landlord proposes to rely on condition 4: within 3 months of the closure order (or if the order is appealed: within 3 months of the conclusion of the appeal).