The relationship between the length of the juvenile period and nine olive seedling parameters (plant height, diameter, number of nodes, lateral shoots, internode length, leaf length, width, area, and shape index) was explored in 287 plants belonging to four different progeny. The traits were measured at two timepoints: after the plants had completed a forced growth cycle in the greenhouse/shadehouse (15 months after sowing) and after one growing season in the field (27 months after sowing). Strong linear tendencies of most vigour traits (mainly plant height and diameter) with the time of first flowering were observed. Leaf traits measured after one year in the field were also related to the length of the juvenile period, but not the same traits that were measured the previous year. Strong positive correlations were observed between the parameters studied. All results are discussed in terms of selecting the best seedling traits to be used as pre-selection criteria for short juvenile period during early stages.