First up, no one has seen any evidence that _any_ suites are in service yet. However, I would expect that LHR-HKG/NRT will get them before LHR-CPT (which is still only a seasonal route and may not run during the end of March). LHR-CPT may also still be an A340-300 which is probably going to be phased out in favour of the -600s and therefore may well not get the suites at all.
BC