If I hold to 6 points, conquer the other battlefield to 7 points and then play the baron scoring the baron pit for the first time in the game do I move to 8 points and win?

Yes, you win the game.

Here is the step-by-step breakdown of your score progression and the rules governing the final point:

1. Scoring Sequence

• Start of Turn: You hold a battlefield (scoring 6 points).
• Conquer Action: You conquer the second battlefield, bringing your total to 7 points.
• Playing Baron Nashor: You play Baron Nashor, which adds the Baron Pit battlefield token and moves him into it. Because you have not scored the Baron Pit yet this turn, this counts as a Conquer (Rule 464.1).

2. Why you reach 8 points and win

According to the RiftJudge FAQ #4108 and Rule 466.1.b.2, when you are at 7 points, you are eligible to win by scoring your final point via a Conquer action, provided you have scored every other available battlefield that turn.

• Requirement: To score the final point through a Conquer action, you must have scored all other battlefields in play this turn.
• Your turn: You have scored the first battlefield (Hold), the second battlefield (Conquer), and finally the Baron Pit (Conquer). Because you have scored all three battlefields this turn, you satisfy the requirements for the winning point.

Summary

Because you have now scored all battlefields in play during this turn, your action of conquering the Baron Pit satisfies the criteria to gain the 8th point. As soon as the Baron Pit is scored, your point total reaches 8, and you win the game.