Been a whole since I checked up on this thread, apologies for the extended delay.
Practice, of course. Even mentally strenuous jobs have lots of free moments that you can fill with tulpa thoughts. You can say hello and hug each other on the walk to the bathroom, or while you have lunch. Unfortunately you can only really focus on one thing at a time, and some things must take priority over others. You can decide what you prioritize, though, so don't get yourself down thinking about what you're missing when you could be thinking about your tulpa instead.
This is the essence of the practice. Coping with reality means you can face it directly, means you can see reality better, reveals that coping and the methods one uses to cope are real. "Pretending" is only a matter of perspective, and the perspective of a tulpamancer is that there is no such thing as pretending, only creating.