If you come down US 75 toward Dallas stay on it as it turns into I-45 at downtown going toward Houston. South of Dallas you would then take I-20 west to I-35E to Waco. Maybe 3 miles farther but much easier, trafficwise. Again a frequent route we take.
That is much better than trying to cross over from US 75 to I-35E downtown. Heaviest traffic will likely be from McKinney thru Richardson.
Headed that way Friday morning, during morning rush hour.
Be aware they are predicting heavy rain/storms tomorrow, especially later in the day. All bets are off if that happens.