Let me give you to opinions and expierences, Using molasses all the time during outdoor since I have a LARGE supply ...and using it during later phlower when not using chem phertz ...l3ut a plant needs sugars daily, so anytime would l3e good
Blackstrap provides nutrients as well as usable sugars. These things help the growth of the plant during all stages. It also serves as a good chelating agent to help the plant uptake nutrients. I like to use a tsp every gal of water, including all the way through flush, as it also serves as a good ionic solution.