Is it a problem to do your planning session at the 7 month mark? That is the time that works out best for us to go with work and the holidays, etc. I know they won't guarantee the prices then but that fine.
Yes it shouldn't be a problem. If anything by the time you get your BEO back your prices should be ready to lock in since you will be at your 6 month mark.
We had our PS in early May and our wedding isn't until the end of December. We're just now getting floral prices and are still waiting on the BEO, so that's the only part that gets delayed.