With 18 years of experience in keeping and breeding retics I can give the advice and help needed here without guess work or just opinions.
Gender - makes a slight difference in the end size of the retic you chose therefore the end result in enclosure required.
Locality - whether pure or cross bred, the island in which they have come from can determine the growth rate and potential end size.
Feeding - the regime and size of food offered will impact the growth rate in either direction remembering young retics would feed more frequently than adults and the size of food offered to digest.
Heating and humidity - humidity to be around 80% and temps at the hot spot 85-88 degrees F. So for a suitable substrate to maintain this. Coco coir, orchid bark mixed. (Remember when you put a new bag of orchid in some time you get a high spike in humidity so vent out a bit )
Before the big viv- Tubs are fine to use before jumping to a big viv again young retics are much more active than adults (adults can still be very active when out)
Hope this has answered some of your questions. I tend to sell to shops are only males because generally the end size result is more manageable in terms of length and girth.