It should be noted that transfer learning is an umbrella term for many ideas that revolve around transferring what one model has learnt into another model. The method described here is a type of transfer learning called fine tuning.
Another approach I've seen that was really cool is Model Distillation [0], which is basically the training of a smaller NN with the inputs and outputs of a larger NN (where the output is slightly modified to increase gradients and make training faster).