Ok, first, from LK's guide above, with 4 decent engies (say, class A in LK's guide),
Iowa and Monty hits their speed cap at roughly lvl 112. And also, if we apply the '0.2
belt and bulge until you lose the first knot or the second' armor rule, then Iowa
would go at 23/39 or 24/40, while Monty would have 23/39 at speed cap.

As a player started last March on Missouri server and don't play very often, I
currently have 5 engies at lvl 94, 94, 91, 81 and 81. And as a result of having only
one BO, my gunners and BO are now almost lvl 102 (expecting them to reach lvl 103
during the event), and thus my Iowa have a nice shell spread, but runs only 23/36
or 24/38 (with almost no bulge).

In this case it's unlikely for me to wait until they can hit the cap before I use them. I
would like to know some opinions about how fast you think is acceptable for an
Iowa or Monty. Thanks in advance if you have some good advices.