First of all, this is just advice from me personally. I've been training in BJJ for 2 years total and Muay Thai for a little more than that but I did Boxing/Wrestling before that so I know what it's like to train hard. Here is my advice. For starters, there is no too much or too little. If you can only get in there 1 day a month then do it. If you can get in there 7 days a week, twice a day then do that as well. As far as the order goes, either order is going to be beneficial and here's how. Either way, you're not going to be 100%. If you're not during striking, when you are 100%, you'll be a more "conditioned" striker and vice versa.
When it comes to skill level, I'm assuming you're still a white belt and while I've seen white belts beat people at higher belts, that means nothing. At while belt, all you need to focus on is surviving, not getting submitted, and not getting winded or trying to muscle your way out. It'll be more frustrating for a blue/purple/brown/black belt if they can't submit you than it would be if you muscle them off of you and don't know what to do afterwards. Also, stretch daily. I recommend 3X a day including whatever stretches your gym has you doing before workouts. Nothing serious, just 5 minute stretches here and there when you can.
Finally, watch videos. While that won't help you more than 5-10% with your BJJ game, every little bit counts. Don't rush anything either. Odds are, you'll be a white belt for a year (give or take a couple months) so focus on surviving. Finally, when it comes to Muay Thai, do what they say. Shadow box when you can at home and try to pair up with those better than you but also work with people who are new and wanna come out and throw sloppy haymakers or bumrush you from the get go. It's all handy!