Depends on the individual snake, feeding schedule and so on. I can tell you that my female dwarf, a Genetic stripe poss. het. albino (from prehistoric pets), has grown about two feet in six months. She is now over 6 feet, maybe 7 and 19 months old. She has been fed a rat about 10-15% of her bodyweight weekly. I believe a certain person on this forum might say that my feeding schedule isn't enough and that I should feed more but It's working fine for me. My snake is growing steadily and is not aggressive or skinny at all.
/E
Edit: also, Welcome to the forum!