In all honesty, if this is something you have to ask about, then you probably shouldn't be breeding her at all at this point. It sounds like you still have a lot of areas and things to consider and research and understand first.
Aside from the fact that chances are not in your favor that a 6 month old could sire a litter, why would you want him too? He's still a puppy. You have no way of knowing if he will possess qualities as an adult that even
should be bred.
Also, part of being fully prepared to take the step to responsible breeding means having a good knowledge of your female's heat cycle and when she would be fertile for breeding. You are considering breeding her and you aren't even sure how to tell how long she's been in heat...
Do you have a breeding mentor? These are issues he/she should be there to guide you through "in person." From the sounds of it, you may benefit from progesterone testing to help you better evaluate your female's fertile period.