I like to get home, sort my van out,have a bath and get my tea then go to the gym. I could never go straight from work.
It doesn't matter when u go as long as you go consistently 3 or 4 times a week and train with intensity. Any less than this then your wasting your time.you ll see no results and you ll get disheartened and give up.
Remember you need a good diet too no junk!fish/chicken/lean beef/eggs/wholegrain everything(pasta, rice,bread, etc), oats, fruit and veg, Greek yoghurt,cottage cheese, milk, whey protein shakes/bars, fish oil, creatine, multivitamins etc.
Ease up a little at weekends food wise but don't stray too far from the above!