This may depend on your current age and your age when you originally took the test. This personality typing system is based on the 8 functions developed by Carl Jung. Everybody uses the same 8 functions, but in different orders and varying degrees of development. But as life progresses and hopefully we mature, we eventually start being more well-rounded, and using our less "natural" functions.
The functions of the typical ENTP are in this order:
N,T,F,S
The functions of an ISTJ are in this order:
S,T,F,N
Other than the You probably know enough about yourself to know you're more a Thinker than a Feeler, but other life changes and function development could easily have you answering as a Sensate when you're an Intuitive (because you may be actively using that function now).
It may help to think back on childhood. An imaginative child or a reality-based child? A "responsible" child or a "head in the clouds" child? As an adult, a detail-oriented "inspector" or an "inventor"? As a child, an introvert or an extravert?
But I do think we change a lot as we age. I used to be much more of a dreamer, but now I am much more grounded in reality (we could go on about why that happened, but I pretty much know).
I think it's really most interesting to watch how we change in life. It also helps give insight into why we may or may not be totally happy in our careers/life.
As to when I took this before - it was probably around 10 years ago, when I was in my teens. :)