The lemon varieties Fino and Primofiori are usually harvested in two lots, the first consisting of the fruit that has reached a suitable size and the second of all the fruit remaining on the tree. The prices tend to fall as the season progresses. It should not be forgotten that the size of the fruits does not cease to increase during this time so that one factor offsets the other. To determine optimal moment for the first harvest, fruit calibre and weight needs to be measured weekly and the percentage of lemons ready for market determined. The prices quoted by the Spanish Ministry of Agriculture and the Department of Agriculture of the Province of Murcia will help growers decide whether the time is right for harvesting from an economic point of view. In this work this moment is determined both for growers who sell their crop on the tree and those who sell their production directly, so that we also consider the prices of the Spanish transport and wholesale market network (MERCASA). From the study, we conclude that as long as total production remains below 600,000 tonnes, prices will be high throughout the campaign. If growers sell their production to a third party, the first harvest should be around week 44. If the growers decide to harvest themselves and sell their crop to the market network (MERCASA), their income will be more stable.