When should I? (in General)

I'm wanting to hire a second minion. When would be the optimal time. I know from the experience of watching Single Minion get married that really late in the game doesn't make sense to hire. I'm around 300k MPR, if I want to hire shouldn't I do it sooner rather than later?

Sooner if you want the minions to be relatively close together in terms of exp. later if you plan on it being just a tat holder of some sort. I don't really think there is an exact optimal time that I ever recall using.

its going to be a wall in the front, with halidon in middle and 20 hp enchanter in rear

If you want optimal growth from hiring decide how much you're willing to spend on a minion and wait until the more expensive hire reaches that threshold.

Otherwise it doesn't matter much.

I personally think it is best to start off with however many minions you want your party to be. Hiring minions is way too expensive to do otherwise unless CBD is not an issue and you are going for the huge boost of EXP at the end of the run. Otherwise, just create your party with the minions you have in mind, and if you want them to be different exp levels just use a Rune of Enlightenment to get the differences you are looking for.

RoS would be awesome if my tattoo wasn't my main damage dealer