Alex makes an excellent point.
If I were in your shoes I'd:
On a lazy weekend morning, plan to open all of the bottles at the same time ... if you have enough decanters to do so. otherwise instead of all four, I'd pair the Croft and Delaforce and later on do the Taylor/Fonseca pairing.
Pour into the decanter and remove the sediment. Pour two ounces of each into Port glassese.
Note the color of each, the aroma, sip it and note the body weight, texture, flavors, tannins and length of the finish. Do the same with one ounce of each, every four hours until you go to sleep. Before heading to bed, close up the decanter. In the morning start the same observations ever four hours with an ounce and do this until the bottles are empty. If you have a good friend who likes Port, invite them over for one of your "tastings" to see what they observe too.
Do the second pairing of bottles unless you have done so with all four at once. If you do this ... see if you can invite a small group of Port loving friends to join you either the first or the second day.
The evolution of these young pups will fascinate you and will be one of the greatest learning experiences you'll ever have with VP. Enjoy!
One key I forgot to mention: when I said "note" I meant ... write down your impressions. Of course, we'll expect a full report here!
