Let's start this analysis with swords:
The 9 months figure I "remembered" appears to have been dead wrong... For a single smith to hammer out a sword it takes between about a week and a month, depending on the size of the blade to be forged.
Optimizing an armorer's facility should begin with the single anvil. 1 anvil can be used by no more than 3 people at a time. One person holds the metal and 2 alternate hammer-blows. Using a simple 2 iron process (one is in the coals heating up while the other is being hammered), means 3 people can hammer 2 swords simultaneously. Share a bunch of anvils per fire and you can scale out from there.
Once the sword is about finished, you need to temper it, which needs the fire and a quenching bucket (it's the rapid-cooling that causes the metal to harden); sharpening comes next, requiring a grinding wheel; and finally "finishing", or putting leather grip on the handle and fitting a sheath to it.
So, your (hypothetically historical) assembly line would be 3*anvil smithies to bang on steel until the steel becomes swords, a grinder, a leatherworker, and since most sheaths have some metal in them an extra smith to bang out those small parts (that don't need the level of craftsmanship a blade does).
Since you are referring to "weaponry" and not "swords", you probably want woodworkers in this armory to make axe handles, flails, spears, etc. The metal parts probably need an anvil at the swordmaker's area since you don't want the spearhead/axehead to break the first swing any more than you want the sword to break first swing. Armor tends to need lots of detail work. Sure, you could get 2 people working together on either the metal or leather parts of the armor, then you need to fit them together.
Finally you don't mention whether or not these will be magical weapons/armor or just "regular" arms and armor. Assuming (for completeness) that you plan to do magical arms/armor you will then need a significant number of magicians (who I'm assuming won't work cheap) to enchant the items, and the quality of artisans churning out the arms/armor need to be better since you can only enchant masterwork weapons.
As for an answer to your question, if your character has 8 followers, I would cap the "lackeys" at 2 per follower since realistically you would have a follower and 2 lackeys at each anvil. Other non-forging tasks would be tackled by splitting up the "lesser" work, but for the sake of mechanical simplicity a follower would take anywhere between a week and a month (let's figure 3 per month for smaller blades, the poor followers can't keep up sprint pace for too long a time) for each sword solo, and lackeys helping will cut the time anywhere from 1/2 to 1/3 the solo-time per sword depending on how much help he gets... but I'm sure the broken craft/profession rules would suggest that 1 follower could take the assistance of 100 lackeys each armed with a typewriter and bang out the works of Shakespeare in under a week... however, I would tend to house-rule any realistic attempt at that economy to make it feel "right" to me anyways so your mileage may vary.
But that's just me; I would suggest that you take the "realistic" approach above, then look at what your campaign's story needs and modify accordingly.