While I obviously don’t know your exact location, Thorpe is only 2h 56m from the Sheffield marker on Maps (I assumed Sheffield as your approximate location based on your profile), which would mean to get there for 10am, you’d have to leave at about 7am if you wanted to get there for bang on opening time, probably slightly before 7am if you take into account the time required to actually get into the park. I don’t know how long you’d typically take to get ready, but if you literally did the bare minimum of your morning routine in your house and took breakfast in the car with you (we’ve done this before), I reckon you could quite easily get up at 6am.
From my experience, getting to Thorpe at around opening time or only slightly before is adequate, as their policy when we last arrived there super early was to hold you at the Dome area until 10am anyway, so arriving super early wouldn’t make a whole lot of difference. On my solo visit September, when I was getting into the park itself at 10am or slightly later (so I didn’t arrive phenomenally early by any stretch), I got on 4 or 5 rides within the first hour. This was admittedly a Tuesday when the kids were in school, whereas it appears you’re planning to visit on a Saturday, so it might be slightly different for you, but from my experience, arriving at opening time is fine.
If you’re concerned about ride count, knocking out Stealth & Inferno first would be my advice. They always seem quietest in the morning, weirdly… particularly Inferno, which can amass quite a queue later on. Unless you get there later, in which case Swarm might be a good shout, as the opening time crowds would have moved away from it to the other rides.
