1/2 Gal Pot & sexing?

Is a 1/2 gal pot with regular soil to small to keep a plant in until signs of sex before transplanting

Nope but I wouldn;t. I use styrofoam 32 oz cups and go directly to 5 gal airpot when plant oversizes it usually about 2-3 weeks veg. They do need room for roots and could make them small. The tradeoff comes down to room.