On Princess there are two sets of documents. The first you generally receive about 2 weeks after final payment. That includes your "Know Before You Go" booklet, shore excursions, immigration forms and other general information. If you've filled out the information on the Princess Personalizer for immigration, you don't need to do anything with those forms. Then, 2-4 weeks before you sail your actual cruise documents will arrive. These are your actual tickets.
Unless your TA has indicated to Princess otherwise, your documents will come through the TA.