@anavalencia - Hi Ana. Thank you for your kind words. Much appreciated. It is easy and a labor of love for me. I know my lengthy answers annoy some folks, but I find that brief answers often lead to misunderstandings so I try to be thorough. I apologize for my delayed reply, but I have been busy with my paid consultation work this week.
I don't have a good explanation for the leaf discoloration that you see. The small spots are natural blemishes. The larger patches of brown may, in part, be physical in nature from rough handling, pets or possibly exposure to a draft when the door is opened. It is also possible the damage was done before you purchased it. If none of those seem to apply, then there is some disturbance with the roots.
The key is how well the new growth does. It should be spot-free. Trimming portions of the older damaged leaves will not cause further deterioration of those leaves, but it may not prevent further discoloration either. If most of a leaf is discolored or otherwise unattractive, cut it off for aesthetic reasons. It will have no bearing on the health of the plant.
All you can control is light and water. Keeping it close to and in front of the window is fine. Unless you live very far north, the shorter days should not have a big impact on the plant' although the growth rate may be a bit slower. A grow light might help a bit, but it is not at all necessary.
Watering may be a bit more tricky. If you added soil to the top of the original rootball, remove it. Then allow the top half to one-inch to dry before watering thoroughly.
It often takes plants a few months to settle into their new environments. I suspect yours may be struggling a bit because of its apparent mishandling before it got to you. Be patient and I think it will do just fine.
