I had the same problem with my two boys. It does get frustrating at times. Remind yourself that this is the last thing that he has to accomplish to move from being a baby to a toddler. This is a choice that he will make even if you want to do if for him. If you are looking to go in the work force than I suggest you get a timer one that you might use in the kitchen a min. one. Give John liquid, juice is a good one. Than every ten min. set him on the potty and if he goes give him lots of praise, treats work well to. If he wets in his pants don't make a big deal out of it this will discourage him on using the potty.
It took me three to four months with my 3 year old to use the potty when I set down and put my mine to it (Finally had it with changing poppies). I even got him under pants with the rubber pants. I switched out with pull-ups when I got tired of washing undies. The truth is they do it when there ready. The best things you can do are support him and not make a big deal over the wet pants.
There is one more suggestion as to your dilemma with the childcare. Work at home especially if you�re trying to have another baby. This way you are not pressured on your child raising tack-techs. I have done some research on this and have found the best solution for myself were I can stay home with my three children. I do not have to trade my time for hours with my business or my family. I love what I am doing and would like to tell all stay home moms about it because I would like to help you stay home. I use to be a nanny and it broke my heart to see the mothers hurt for leaving their children and the child would hurt also. It takes a special kind of person to do what I do for work. If you are interested in this just drop me a note.
Good luck on the potty training and just remember that this time won't last for long and before you know it your Johnny will be eight-teen and going off to college to start his own life. This is just a small optical that us moms have to overcome and who knows your son better than you.
G.