The competition for roles as a medical science liaison is very tough, as with most non-clinical roles for former clinicians or scientists. Clinical roles are almost always easier to obtain than non-clinical, due to supply and demand.
Requiring the longest maturity time, the Guatemalan avocado needs 15 to 18 months to change from its flowering blooming period to a full harvest. On average, the tree blooms in March and April, but will not be ready for harvesting until the year after between September through January.
If you plant a seed, and are skilled enough to graft the seedling when it is approximately one year old, you could, with good care, have a tree producing avocados in 4 to 5 years after planting the seed.