Hi Jerry,
I remove bark on anything I deem large enough to support the air layer with out assistance.
The small stuff I do not remove a ring but slice or score it lengthwise.All these are on second year wood,on first year I wouldn't bother.
I get the strongest,quickest layers from equinox through solstice.I stop placing at the end of June.Last year I stopped counting layers placed when they got into the high 80's,I did note I had a high failure rate on anything placed after mid July.
Hope all's well down there.