Call_me_jorge said: "Shows normally don’t launch a tour until one of two things happens; a) the broadway company recoups its initial investment, or b) the broadway company has closed."
Option A and Option B both tend to be coincidental things, by nature of it taking 16-24 months to get a tour out.
Most presenters' subscription seasons are set a year or more in advance, which is the primary reason why a show can't open in March and launch a tour that October.
Producers start courting tour bookers and presenters before the Broadway opening. Entities that control touring houses like BAA, IPN, and Nederlander often invest in exchange for preferential treatment when it comes time to book a tour route. Sometimes tour producers/GMs like NETworks and Troika also invest in shows.
The actual planning of the tour usually doesn't begin until after opening night because if something seems like it will be hot on Broadway and then it tanks (Tootsie, for example), then what was once planned as an Equity tour could go non-Equity, or authors want to rewrite before a tour, or there are now hotter properties that the presenters would prefer. And unless something has the brand level of BTTF (famous movie AND did well in London), nobody's going to program a show until they actually see it.