T-Mobile USA late on Wednesday released some preliminary first-quarter results that it says show its turnaround efforts are starting to take hold. The company said that its total customer base grew to 34 million in the three-month period, an increase of 579,000. It still lost nearly 200,000 contract customers, though that’s narrower than the 515,000 postpaid defections it saw in the prior quarter. Its rate of churn among its contract base narrowed to 1.9 percent, the best such figure in four years, T-Mobile said. “These results display positive momentum and the first positive branded growth in four years,” CEO John Legere said in a statement. “We have made material progress in stabilizing our branded business in Q1, which provides a solid foundation to build on with the new Un-carrier customer offers we launched last week across America.”