When is a good time to start to floss the sides of the two teeth directly adjacent to the dental implant healing cap? a one stage approach was used yesterday?

You have a fresh wound that is healing. Avoid traumatizing the area until sutures are removed and the area has healed. These post op directions should be addressed with your treating surgeon.

There is much space between the healing cap and the adjacent teeth to keep clean with a interdental brush or a WATERPIK. Just be gentle in area till full healing occurs .Always follow post operative instructions.