To try to answer your questions,Trevor.
The E. oxypetallum is a large, unruly beast (see first photo) that produces masses of flowers in mid summer.
The hybrids are relatively small as yet (second photo is 'JT Barber', third is 'Elektra on the left and 'Desert Moon on right) and have only flowered for the first time this year now, in May, which is much earlier than the species.
I have been feeding them with a balanced liquid fertiliser at infrequent intervals (meaning when I remember to do it!) starting in the spring and ending after the large one stops flowering, usually sometime in Sep. During the winter I reduce the watering, just keeping the compost moist.