Battlecruiser availability and Vanguard's uncertain future

Would Britain immediately send its three battlecruisers east to counter the Kongo class, and would that accelerate HMS Vanguard?

Not immediately: Renown remained in refit until August 1939, while uninterrupted or accelerated King George V- and Lion-class construction might remove the circumstances that produced Vanguard in her historical form.

Battlecruiser reinforcement could follow, but Renown's refit prevents Britain from deploying all three ships at the outbreak of the counterfactual war. Immediate availability leads into a second question about procurement. King George V- and Lion-class work would continue or accelerate without the interruption caused by the historical war programme. That sequence could remove the circumstances that produced HMS Vanguard in her familiar form.