Something like this:
$.when(
// first one
//data = data1
$.get("your-url-1-here"),
// second one
// data = data2
$.get("your-url-2-here"),
// third one
//data = data3
$.get("your-url-3-here"),
// fourth one
// data = data4
$.get("your-url-4-here")
).then(function( data1, data2, data3, data4 ) {
//Do something with data1, data2, data3 and data4
});