When to book UC to NYC next July using miles?

Hi,
I'm looking to use our miles for the 1st time, for 3 x returns to NY next July (may fly back from IAD?).
Normally when I book (paying cash), I am there on the day that they become available (mainly as its always been MCO in the school holidays). But this time I am looking at early July for 7-10 days (Just before school holidays start).
Would this be the best time to book, or do they tend to hold back and only release 'mile' flights when they think they need to?
I also have 'Free companion rewards' (x2) and 'Econ to PE free upgrades' (x2) - Don'y know if this helps???
Any advice would be appreciated.
Many thanks,
I'm looking to use our miles for the 1st time, for 3 x returns to NY next July (may fly back from IAD?).
Normally when I book (paying cash), I am there on the day that they become available (mainly as its always been MCO in the school holidays). But this time I am looking at early July for 7-10 days (Just before school holidays start).
Would this be the best time to book, or do they tend to hold back and only release 'mile' flights when they think they need to?
I also have 'Free companion rewards' (x2) and 'Econ to PE free upgrades' (x2) - Don'y know if this helps???
Any advice would be appreciated.
Many thanks,