For a descriptive answer, the buds will start to stretch out, sugar leaves will grow bigger and into fans, there will be a lot of growth In between nodes/calyxs and leaves, this will all start to happen right away, the plant won't really hermie because it won't be a light leak it will be an actual light schedule change, the leak is confusing to the plant and stressful whereas the switch back is abrupt and the plant just starts to stretch and grow green leaves again no flowers so no hermies.
In basic terms right away your plant will turn its energy away from producing buds/thc and it will turn what you have into larf within a week or so.