Cycas Revoluta leaves turning yellow
I bought a massive Cycas Revoluta about 3 weeks ago and its trunk diameter is 8 inchs. I kept it in a massive pot with 4 draining holes at the base of the pot. I over-watered first time when I kept it in the pot to let the sand settle firmly in the pot. Later I came to know that they must not be over-watered. After a week the bottom-most ring of leaves turned yellow then on the following week heavy rains occured and another ring of leaves turned yellow from bottom second. Then I tied a platic cover around the trunk covering the sand and pot so that no water can get inside it. When I search on google some say NOT to cut yellow leaves until they turn brown while some say to cut all the leaves except the top most leaves to encourage new flush of leaves. I felt greedy of its beauty so I chopped the bottom-most leaves that turned completely yellow on the 3rd week.
I have a pot mixture of 10% perlite stones,20% normal home sand that I added to 70% black sand that came with the sales plastic packet in which the Cycas was kept and sold.
It will get 5 hours of sunlight if there is no trace of a cloud from 9am to 2pm. Hardly it will get 2 hours of sunlight through the moving or steady clouds.
What could be the reason for leaves turning yellow? Is it because of over-watering by me? Does it mean that leaves will turn yellow even by heavy rains? Will the leaves turn yellow all the way to the top ring of leaves from bottom ring of leaves?