Most avovcados will mature on the tree in the fall to late winter. Black skinned varieies such as Hass will hold on the tree until May or June. I am still picking some Hass right now. Many green skined varities will be harvested in Dec thru March. Pick one or two at a time and leave them at room temp until they get soft . This may take up to two weeks depending on the varity and the season. The longer they remain on the tree the less time it takes for them to fully ripen once they are harvested. A particular variety will always ripen or mature at the same time each year. If you know exactly which variety you have I could give you more particulars on its harvest time.