Very little arrives for a person whose Saturdays are booked eleven weeks out. The offer comes and the answer is already no, before anyone has finished the sentence.
Openness sounds like an attitude and behaves like a diary. The friend who keeps one evening clear is the one who ends up at the thing that changed their year. An invitation needs somewhere to land, and a full week offers it nowhere.
Leave a gap in tomorrow. Not a plan, not a resolution — a genuinely unspoken-for hour. Something may want it.