That's a good call. Monk PrCs can be great, and they generally only require a few levels of Monk.You know, because you can never have too many alternate rules systems in one build!
90% of the best Monk features, only 2 levels! Its like Diet Monk!
So you're usually going to end up with about +6 to Str from various buffs starting at around level 4 to level 10 ish?
About that, I guess, maybe more, maybe less- I never keep track.
Another boost can come from build. Kensai, as I'm sure you're aware, is a Monk-friendly PrCl- IOW it doesn't keep you from continuing Monk advancement. Besides it's weapon of choice rules, it also has an ability that grants a conditional untyped +8 Str bonus, which makes for a nice boost.
The condition is that it's a 1/day boost...unless you make a Concentration check. With Con as my 3rd best score and with Concentration as a class skill, my Monk/Kensais tend to get at least one extra use per day out of it.
What strikes me is that at this point, your polearm using, javalin throwing monk isn't making use of the signature monk ability of beating people up with his fists, which is the main reason people seem to want to play a monk. Moving around the battlefield adding chip damage here and there while tripping or supporting frontliners from the second line is something that can be done better by a fighter with Boots of Striding and Springing, or a barbarian.About that, I guess, maybe more, maybe less- I never keep track.
What strikes me is that at this point, your polearm using, javalin throwing monk isn't making use of the signature monk ability of beating people up with his fists, which is the main reason people seem to want to play a monk...
If were going for a character that mixes armed and unarmed combat, the question of why to use a Monk still exists, as there are at least two classes (Totemist and Swordsage) which are in competition with the Monk class...I have never thought of Monks as merely unarmed combatants. Many of the iconic martial artists mix unarmed and armed techniques: Bruce Lee had his nunchuks; Shaolin Monks use swords, spears, halbards, staves, etc.; Jackie Chan uses anything within reach.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.