Read the data shets to determine the replensih rates. I am not familiar with the tetenal minilab chems you show an interest in, but they are a most capable firm.

The data sheets should give you a clue as to how concentrated they are, and the level of dilution to make working tank solutions and replenisher solutions.

Developer is the tricky one to work with without a starter.

The developer starter emulates the chemistry that usually builds up from processing films, namely trace elements of bromide and iodide ions that are a side effect of developing the film silver to an elemental state, along with pH adjustments.

I use a developer for b&w work, diy harveys 777 from the unblinking eye recipe that you 'season' by feeding it a couple of fogged films as it's first step after mixing.
After the first batch, you save some the overflow from regular replenishment, and then when mixing a 'fresh' batch again, feed in the old overflow, rater than seasoning with fogged films.

A similar strategy may work here, though tweaking pH to comply with the data sheet guidelines may also be required for in spec results.

C-41 bleaching goes to completion, so I don't think you can over bleach c-41 with a too active bleach ala no starter.
Read to see if the first tank solution is diluted replenisher with starter; dilute and skip the starter, and see what you get.

Fix is fix. Most colour fixes mixed to tank solutions are not strong enough to worry about overfixing.
With c-41 you don't want any silver left, so too strong is likely not a problem, although I have not ever heard of a fix starter.

Using cheap drug store film deals for 35mm trails c. and shooting a macbeth chart will go a long way to get your processing tuned up before feeding it important 4xx5 shots.

As to the processing, I would consider making a roller arrangment of some sort to try to keep the outside of the big drum in contact with a water bath, for the bulk of the 3:15 when temperature control is most important.