Yes it's totally fine to space Femara out! And yes, it's the best of the best tactic that there is. I would consider filling the prescription just because sometimes if you don't do it quick enough, they won't fill it for you. Plus you'll have it on hand if you get a wild hair and decide to take it anyway. :)
But I do want to urge you not to read ~too~ much into that progesterone number. It is SUPER common for people to have ovulated later than they thought and their prog level seems low but then they go on to get a BFP.
I actually have two December babies and yeah it's a lot, although I do find it adds to the festivities of the season I'm often financially pressed more than I'd like to be and occasionally someone gets shorted in the present department (usually my oldest, for which I feel terribly guilty even though he's 26 years old and claims not to care) So I completely understand the desire to take a month off from TTC.
What I would do here and now is just regroup and see how you feel. See if you're pregnant this month, don't despair just yet. Then if you aren't, you can decide to take a month and do diet, get your weight where you feel happy with it, and so on. Sometimes we pink swayers (control freaks LOL) feel like we have to have this full 10 point plan drawn up but there is all the time in the world to make the decisions as they come up - no need to know now what you want to do in a week or a month!! But do fill that prescription so you have the ability to change your mind suddenly and it will be all good.