My first ever cycle was sust 250 for 8 weeks. It was heck of a kick start for a virgin body to gear. Strength, sex drive and all around well being is going to kick in fast. With that said, two things happened to me.
1) The pip from the sus was unbearable for a virgin muscle. It got to a point were I had sit with one butt cheek down on bench.
2) Test flu hit me hard on week two.
I am not against your first cycle being sust, but 12 weeks is long and you don't need the oral. Safe option would be test for 12 weeks, but again I really enjoyed the gains and the feeling on 8 weeks of sust.