The rule says:
" two years of practical maintenance experience on operating aircraft
and completion of a Part -147 approved basic training course."
I have looked at the AMC's and the GM. I can't find anywhere a statement that says it must be completed after the approved basic training course.
However it is only by completing an approved basic training course that you can have the reduction to 2 years experience.
You could try and argue form the ELGD:
D3.2
‘Recent Practical Maintenance Experience’
All applicants must have gained at least one year’s
experience on aircraft typical of the category or
sub-category applied for. Of this one year’s experience,
six months must have been gained in the 12 months
immediately before application. The remainder must
have been gained in the 7 years before application.
Good luck 