The whip itself will tell you when it needs a dose. It doesn't go by the calendar.
Condition your whip when it feels relatively dry and stiff. Don't overcondition it, because this will weaken the strands over time.
Usually, the fall requires conditioning more often than the thong. Wipe on, leave it for a few minutes, then wipe off with a soft rag, stroking from the handle toward the lash.
You do not need to condition the whole whip every time you do it -- just the end. The handle is rarely conditioned.
As for which product, there are many good choices out there. You can use Pecards, Fiebings, Jay-El, or Dr. Jackson's Hide Rejuvenator.
One pro whip handler (Joyce Rice) used dish soap for the lanolin in it.
Whipmaker Victor Tella uses the Armor-All silicon wipes you can get from an auto supply store.
(The old cowboys used to say the sweat on your hands is the best grease.)
But whatever you do,
DO NOT use Neatsfoot Oil!
It chemically "burns" leather the way gasoline will burn your bare arm.
Swinging from a whip will stretch the leather, making your whip wrinkle up like taffeta afterward.
The whips used in the Indiana Jones movies have nylon rope cores or aircraft cable with an overlay of kangaroo.
They are made specifically for swinging, not for cracking.
It's a great fantasy, but reality is elsewhere.
Simply put, swinging on it will kill your whip. Don't do it.
Or you can contact me.