Don't get too ahead of your self, Astronomy has a huge effect, possibly the single largest one on sea travel, engineering gives a +50% movement bonus on roads to foot units and a +25% to cavalry and tanks, which doesn't make that much difference, especially not in war, where you're travelling across enemy roads.
Astronomy is more akin to railroads.
On that subject, a beeline to railroads seems practical after RP, we get Engineering and Gunpowder to begin with, and rifling is one tech away, and we get a large boost to production, railroads (obviously), a 50% increase to improvement building, cannons and machine guns.
Although, it's a pretty costly route, but not short of benefits.