The best advice I can give is take the stud back to your friend immediately.
Then take a long hard look at whether you are responsible enough to plan a mating.
Take the intervening six months to make up your mind and if you feel you will be going ahead, get the bitch health checked and look for a suitable experienced and proven stud.

If you go ahead now with a maiden bitch and and an inexperienced male you could end up with two very damaged dogs if he does manage to penetrate and she panics.
And I would not like to be in the vicinity of two such strong dogs if things do go awry.

Sgurr