Below is an extract from JAR FCL which to my reading says as long as you have passed a proficiency check your are exempt from the 15 hours requirement.
I copy and pasted the extract from the web so it should be up to date.
JAR–FCL 2.330 FI(H) – Privileges and requirements
[Provided that in the preceding 12 months the FI(H) has completed not less than 15 hours of flight instruction (which may include skill testing/proficiency checking) on single-pilot helicopters, or passed, as a proficiency check, the skill test set out in Appendices 1 & 2 to JAR-FCL 2.330 and 2.345,] the privileges of the holder of FI(H) rating (for restrictions see JAR–FCL 2.325) are to conduct flight instruction for [the issue of]:
(a) [a] PPL(H) [ ]
(b) [ ] a CPL(H), provided that the FI(H) has
completed at least 500 hours of flight time as a pilot
of helicopters including at least 200 hours of flight
instruction;
(c) [type ratings for single-pilot single-engine
helicopters]
[(d) a helicopter] night [qualification]