I definitely wouldn't recommend it.. a cheap-but-decent PH meter costs maybe 40 bucks and is definitely worth the investment.
I'd rather get one early on and make sure the plant is healthy, than come back in a few weeks, posting about nutrient-deficiencies and how to solve that..
..same goes with EC by the way, so best get a dual-purpose PH/EC meter.
Yes, i come from the hydro side, where this is much more important, but i'd rather do it right, right away, than having to chase problems after problems, and then having to buy them anyways (and have a sick plant).