For your accreditation you need to teach a new ringer who started handling lessons after you attended the day course, and with whom you have used the ART training techniques.
However, if you have ringers who you have taught previously who can pass all the requirements for Level 1 of the Learning the Ropes scheme and the handling assessment in the LtR Ringers Personal Progress Logbook, then you can certainly order them a LtR certificate. It would be unfair to discriminate between ringers in a band depending on when you taught them.