I do something similar but stop buying ships a bit earlier than that, as my economy is always going down the drain at the start so I need to keep a buffer of funds. If I run too low I try to trade tech as much as possible to keep afloat.
The biggest difference I make is with the tax rate. I keep mine deliberately low, which keeps happiness and therefore growth rates up. I build an entertainment centre fairly early in the development of any high (10-12+) PQ planet, and then keep the tax rate such that happiness is >80%, ideally 100% (for double growth). I feel the extra population more than compensates for the lower tax rate - and you also gain in influence and available troop numbers.
Depending on the map and the starting point, my first or second purchase is often a scout ship. I also priortize getting engines up to the first +10 speed tech, and sensors 1 also helps a fair bit.
Edit: This is with beta 4a - if you're playing 1.0X then the growth rate isn't a big issue.
