When to leave older dog and new puppy together

Hi all,
I am really hoping I can get some advice.
We have a 5 yr old staffy male fixed and a 13 week staffy cross female. They have been getting on well only one major tell off from our older staff where he pinned her in the kitchen no one was hurt luckily.
We are at the stage now we really want them to be together full time when we are at work. I am just worried that if we arent there to stop any disagreements things might get out of hand.
She keeps biting at our older dogs jowls and they are now chapped and bleeding and i worry he will snap if she keeps going.
Any advice help on this matter will be muchly appreciated.

Tough question there and really hard to answer without seeing the dogs interact together. I personally would keep them apart if I were out. Is there a behaviorist in your area you could consult?

yes this is hard to answer but I personally think that 13 weeks might still be to early to keep them unsupervised together during the day. Maybe start slowly with 30min and working your way up?

Thank you Jstaff and Cecil15 for your reply. I spoke with our dog trainer 2 weeks ago and he thought they should be left together then but i really didn't want to risk it.
Now she is getting really big as she also has lab in her she can jump her enclosure we had her in to be with him. I guess in that sense she makes the decision for us!

I don't want to come home to blood shed because she didnt listen to him when he subtly told her to bugger off.