Unless you have a big or very engaged audience on Facebook, contrary to what seems to be popular advice, avoid large amounts of organic posting.
It depends on your business, but posting 1 time a month could potentially be enough. It all depends on your goals, what content you have available (and it's quality.)
Instead, focus your efforts on Facebook advertising.
This way you can get to your ideal customer (that isn't already acquainted with you) and if you've been running your business for a while, using a good quality lookalike audience is your best bet.
Get clear on your customers biggest desires, and give them something that satisfies their desire.
For lead generation, offering some type of lead magnet and creating a sales funnel is the best way to go.