Assuming you are in possession of an ATPL 4 stripes would be fine, 3 stripes for a CPL and I think 2 stripes for PPL (I am not sure about this one), at least that is what cadet's are allowed to wear, once they have gone past the PPL stage.
The school where I trained also gave the students (those on the professional track) one stripe after first solo (and then deducted that from their account
).