Did the Lord Jesus' disciples prepare the passover on the 14th so that they could eat it with Him that evening or not.....according to the text?
Yes, the NT Passover was prepared in an upper room on the evening that began the 14th and was observed after supper.
We don't know what they ate for supper but after supper Jesus observed God's NT Passover, which to this day is observed by many of us since he said do this in remembrance of me. Many of us do.
And it only takes a short while to prepare unleavened bread and wine to be taken after supper. In fact, I buy unleavened bread and wine ahead of time so that after dark on the evening that begins Nisan 14 all I have to do is break the bread, give thanks, pour a little wine, give thanks and I have renewed my contract with God for another year.