Choco,
You should remove the gravel now. Why even risk it?
When you change you pretty much have 3 options. Bare bottom, river rock, or sand. Bare bottom is obviously the lowest maintenance, yet it is less than pleasing aesthetically.
Sand is very clean and natural, Yet a bit more hassle when doing water changes.
River rock is the dirtiest of all, with the spaces in between the rock allowing waste to get trapped keeping it away from the filter. River rock needs more maintenance, I.E. siphoning between the rocks to get trapped waste.
It's up to you, but if you asked me I would recommend sand because it is clean, and looks very natural.




