We were in L102 on the Regal a few years back and LOVED it.
I did a lot of research about the forward facing balcony cabins before booking them. You generally CAN use the balcony while the ship is moving. But there are sometimes issues with open blinds causing the light from inside the cabin (which is right above the ship's bridge) causing visibility issues on the bridge at night due to glare. I think this is why some have occasionally reported being told that they can't use the balcony while the ship is at sea.
If you keep your balcony door closed, and the blinds drawn if it's night time, you should be able to use it anytime you want. Wind can be an issue when the ship is underway though, unless the ship is traveling the same direction of a strong breeze, which actually makes the big balcony quite pleasant, almost as as there is no wind.