Start whenever you're ready and as early as possible so you can build an ample stash prior to the start of your work. Direct latching and pumping is very hard because you have to dedicate one boob to your kid and one for your stash. Ideally, if you still plan to have your kid directly latched on you occasionally, you should hold off bottle introduction until around 3 months so as he/she won't refuse nursing from you. If you really plan to give your kid the bottle at an early age, opt for the soft ones like Pigeon Peristaltic, Comotomo, Tommee Tippee and others. Stay away from Avent as their teats are too hard, as per my experience with my baby.
You may try storage bottles first. If you think they're not enough, then that's when you can get disposables. Some people use trays too. My baby was fed through the bottle because i used to work then in the office and she would latch at night. Luckily, we didn't experience any nipple confusion
If you're going back to work, you may wish to start storing 1 month before. I myself latch during the daytime and my CL bottle feeds ebm to my LO in the night, no nipple confusion and she is still latching very well. (My LO is 3 weeks)
Basically, if you start working, that means going back to work, you can start storing breast milk.