What do you mean by 'proper bike'? If you're new to biking, you probably don't know what you need.
With a height of 5'9" or 10" and a 31" biking leg length, the 52 is likely to be too small in the longer term unless you're racing (and maybe even then). You can raise the seatpost a lot, but you're likely to feel cramped on the bike because the top tube is too short for you once you have a couple of hundred miles on the bike. It takes time to get conditioned to the bike.
A lot of new riders are afraid to lose contact with the ground, so they like low seats, and that puts them on smaller bikes. Riding, though requires your feet to get off the ground.