I have done Yoga several times. Its not like traditional yoga. The instructors do yoga as a "second job". So they may be OK doing yoga but I have found some to be lacking. For example, "Do the one where your backside is in the air," meaning "down dog". LOL
Yoga on the beach was 11 am at the adult beach as I remember. You do not bring a ship yoga mat but bring a towel or two to use.
Yoga on the ship. I have done it poolside in the rain. Early on in the cruise and very crowded. It was approx 7:30 AM. You meet at the fitness center to get a mat. It was held in the spot where the characters dance during the sail away party.
I have done it with 2 other people in the fitness center around 1 pm mid cruise.
And I have done it on the fwd topside deck at 7:30 AM late in a cruise and it was crowded.
You may need to look at the fitness center schedule for exact times.
Being a guy that does yoga I often get ribbed and odd looks from others. I remember doing yoga on the Dream and the energetic 20 something fitness instructor looking at all of the ladies saying very enthusiastically, "good morning ladies" and then turning to me and saying snidely, "and gentlemen." But every time he came over to me during the yoga session he couldn't critique me. Especially when I knew what a vinyasa was.
If you want an exact yoga session, the cruise won't give you that. One trip a lady in the group was a pro and had her own mat! But if you want a good morning stretch the cruise yoga is good for that.
Joe