Perhaps a few words on the germination of the trees: the olive tree bears buds both at the end of its branches and in the leaf axils. In any case, leaf-bearing shoots develop from the buds at the end of the branches. Whether leaf-bearing or flower-bearing shoots develop from the buds in the leaf axils depends on a majority of factors that humans can only partly influence (e.g. by fertilizing and watering).
Mainly, it depends on the weather and, in particular, on how many hours the tree had cold in winter. Cold favors the development of leaf-bearing shoots and warmth favors the development of flower-bearing shoots. In addition, the development of flower-bearing shoots is promoted by the presence of a healthy foliage; only a healthy, strong tree can bear well!