Piastri completed the morning’s running at the Bahrain International Circuit, recording 66 laps during his four hours at the wheel.
He ended the day a comparatively lowly 17th of the 20 runners, more than 1.6s off the ultimate pace.
That was laid down by team-mate Lando Norris later in the day as the Brit added another 52 laps to McLaren’s total.
“Kind of tricky day,” Piastri began when asked for his reaction.
“So far, it seems it’s been a little bit tricky.
“The cars feeling pretty good, we were just trying to get into a bit of a better window and try a bunch of stuff.
“That’s especially what the first day is for – and the opposite is red flags, not ideal, but similar, similar story for everybody.
“So, I think we’re in okay shape.
“There’s a few teams that are looking pretty good early on, but I think we’re pretty happy with how it’s going.”
Running in Bahrain was halted for more than an hour when a power outage hit the venue.
That came at the start of the third hour of the day’s second session.
To that point, Norris had spent much of the session in the garage with attention focused on the rear of his McLaren.
The team confirmed to Speedcafe that the delay was simply a result of the squad making changes to the car ahead of the afternoon’s running.
Once he was able to get on track, Norris shot to third fastest before rising to top spot later in proceedings.
“Everything’s working as it should do, which is probably the most important thing out of today,” Piastri noted.
“Early doors, but I think we’re pretty happy; it’s just very hard to know who’s doing what.
“I think we’re doing a good job of focusing on ourselves and trying to see what changes do what and we’re finding out some good information.”
McLaren headed into pre-season testing as title favourites off the back of a constructors’ championship-winning campaign last season.
However, it is expected to have competition from Ferrari, Mercedes, and Red Bull, with the Scuderia seemingly its closest rival on the opening day in Bahrain.
“That’s what I’m preparing for: to try and challenge for both of the championships,” Piastri confirmed.
“But this is where you put in the hard work.
“The hard work starts a long way before here, but this is the only time you can actually try it out on track and try and improve yourself.
“So it’s been a good morning to try a lot of things, but hopefully it’s an exciting year.
“It’s looking already very close, especially for the first morning of practice… but it’s already looking very, very close.
“I think we’re in for a very exciting year.”
