If you think that down the road you'll have a better PC or laptop, one option would be to play until then on your PS3. For leveling content (and a fair amount of endgame content) it performs just fine. Raiding and occasionally Hunts (basically any time you're going to have lots and lots of players and/or mobs clustered together and need to still maintain combat-speed responsiveness) are where the PS3's specs start to struggle a bit. Until then, the differences between it and a higher end system are slightly longer loading screens between regions and lack of a few minor options on your HUD setup, neither of which is much of a hindrance.

Starting with one platform and later changing to another does mean buying the game twice, once for each platform type, but since each of those copies of A Realm Reborn comes with a month of subscription time, and (in the $12 to $20 range) costs only slightly more than a month of sub time alone ($13 to $15), it's not much of an extra expense. [Note: The Heavensward expansion does not include additional subscription time, so it's a bigger expense to go multi-platform on that purchase. Unless you really have your heart set on playing an Au Ra, I'd hold off on the expansion until you've finished ARR and moved on to either PS4 or PC, then buy the expansion just for that one alone.]