You already should be. If you have been training consistently since New Year or before, you should already be in decent nick. Now the sunshine is threatening to come out you should be building on all the hard work you have done and upping the work rate, fine tuning. Ways of doing this are to train more, going from three to five days a week. Introduce more sets, more weight,Supersets or tri-sets. Rather than split training, go for an all over body workout. If your usually done in an hour, get done in forty five mins. We are not saying it can't be done, we are saying the foundations should already be there. Summer bodies are made in the winter.