When we provided residential organic fertilization services we took an all or nothing approach. We never found the need for the use of “bridge” products. We now manufacture and distribute an all natural organic fertilizer and soil amendments. Our customers represent 1,000s of organically maintained lawns and athletic fields in the Northeast that are being done without the use of synthetic fertilizers or pesticides.
If you plan on using even some synthetics and pesticides than it’s not an organic program and you shouldn’t advertise it to your clients that way. If from a comfort level you feel you need to do it then my suggestion would be to only spot-treat and then apply an all natural organic fertilizer and/or vermicompost top-dress to encourage the soil biology out of its dormancy.