Although its true that being a Captain while under probation is tough, its not such a raw deal. Plenty of companies hire pilots as Captains off the street (lots of corporate and charter), and as long as you know the aircraft, you're ok.
Of course, NJA is upgrading guys without any experience in type. In that case you get 250 hours (or more) before you're actually released as Captain. Except for perhaps the Citation X and Ultra, 250 hours takes about 6-8 months. That does not include Indoc, Initial, Upgrade, IOE etc. In my case that took three months (and I was considered quick). So, in other words, its going to be 9 to 11 months before I actually become Captain (Even though I upgraded and got paid as Captain in 3 months). So I fly a month or two as Captain while on probation - not the end of the world.