@Cathy K. Always glad to calm pilgrim nerves before setting out for a long walk! Preparing is indeed half the fun and helps fill the time until you leave, so prepare away. Remember that no guidebook can dictate your stages, look at the elevations too and make sure you don't try to overdo it and risk injury. Our longest day in March will be 26 kms, shortest 12 kms the day we walk up to O Cebreiro. Not just because it is steep but because it is breathtakingly beautiful so we want to really enjoy it!
As for clothing, this is what I wore in March/April 2015:
https://somewhereslowly.com/2015/06/14/honeymoon-camino/
The only time I felt the cold was on the evening in Melide when my walking gear and fleece were in the wash and I wore everything else but was still cold. We had hats and gloves and polar/merino buffs and just keeping your head, neck and hands warm makes a huge difference. Remember walking warms you up though, layering is the way to go.
And yes, you will have a great time!