The best time to repot any orchid is just when new roots are emerging - with those new growth coming, I'd say your timing is pretty good.
Frankly, I doubt that plant is quite mature enough to bloom, based upon my experience with D. speciosum v.hillii. Given to me as a 7 cm plant in a 5 cm pot, it didn't bloom until the canes were about 75 cm tall.
I can see no benefit in trimming undamaged roots. In 45 years of growing, I've never done that...