Welcome Aliboo:
yorkieagility is right. 2x per day for a five month old is a good rule of thumb for food. Water however, is a must. Right after you feed him, take him out and then put him back in his crate. Is it possible to have someone, like a dogwalker come and take him out at lunch time? They could lead him to his wee-wee pad or take him outside. Whatever routine you choose, you need to be consistent with it each day. So....if he uses the wee-wee pad at 12:00 pm, you can take him out at 5-6 pm when you get home from work. Dogs seem to like routines and schedules, (atleast mine does), with the exception of food. They need a variety of that.
Good Luck , stick to one routine and be patient and consistent.