Step 1 :Translate the problem into a mathematical equation. The cost of the first plan is \(0.21 \times \text{minutes}\) and the cost of the second plan is \(44.95 + 0.08 \times \text{minutes}\).
Step 2 :Set these two equations equal to each other to find the point where the costs of the two plans are the same: \(0.21 \times \text{minutes} = 44.95 + 0.08 \times \text{minutes}\).
Step 3 :Solve the equation for minutes. The solution is \(\text{minutes} = 346\).
Step 4 :Final Answer: The number of minutes you would have to use in a month in order for the second plan to be preferable is \(\boxed{346}\) minutes.