[Ruatha]

I never build BSY'ds as first priority.
I do what many has said here, ER build colonizers, leap-frog and build more planetary yards.
I usually settle for somewhat less than 120% construction rate, 111% is what I'm using now, building colonizers whith 2-3 engines at ER, one each turn, retrofitting them full with engines and sometimes cargo or supply hold.
Somewhat expansive but fast, and in the beginning I have a surplus of resources so it doesn't matter that it costs.