To the OP... don't underestimate the large amount of task loading that you will experience as a novice diver.
And I did just that. Sixth dive, new equipment, used once, new computer ( Oceanic Veo 2.0 ) simple to use, especially in the living room, I couldn't find the exact combination of weights I wanted as I didn't bring mine, I feel like I was fairly overweighted as I sank like a rock, slight current, max depth of 25 meters, lets see that is 75 feet, a little deeper than I've gone ( I only saw 66 that day, for the certs we went to 50 or so, max ), my pressure gauge reads psig everyone else has one in bar, but the math is simple right, 200ish bar is 3000ish psi, 1500ish psi is 100ish bar, 70ish bar is 1000ish psi, 50 bar 750 psi = on the rope at the safety stop prepare to surface. Flash a T with your hands for a 100bar and a fist for 50, OK, got it. Previously we've just flashed numbers 2 5 0 = 2500psi, 8 0 = 800psi, but I got it, lets go!
Hit the water, swim to the buoy, little nervous but far more excited, give my new Spanish insta bud the OK lets go signal and I'm off, sinking like a rock. Get the descent rate slowed, bet to the bottom, depth is 66 feet, I'm good, feel good. Insta bud and I are staying close, he's ok, I'm ok, waiting for the rest of the people including the dive master to get to the bottom. Dive master is down and we are off, swimsiwmswimswimswimswim.
Checking air, looking around, we are off, swimswimswimswim, buddy wants to know how much air I got, what is 2000psi again in bar, and what did they want a T or something like that for 100 but was 50, to late were of swimming again and that ******* divemaster is going through a small swim through, it only looks like it is ten feet or so through, but I'm going over, signal to my buddy I'm going over he is cool with that, up and over we go, venting air, not enough, vent some more air, not enough, **** I'm sinking like a rock now, were the **** is my inflator hose, can't find it, can't find it, CRASH, silt everywhere, look behind me, some guy shooting video, he's gotta love me as I just kicked up enough sand to make a small beach, oh well, dive master is taking off again, time to swim.
Get turned around, checking air, insta bud and dive master asking how much I've got, a little low 1000psi, I thumb it, divemaster says I'm good, well I am, but were at 55 feet and I'm burning through this 15 liter tank like a forrest fire. Hang out for a few more minutes as I can see the buoy line and the boat, so I don't have far to go, look down, I'm at 800 psi, I'm done **** these guys, he looks at my gauge, says I'm good, I signal low air, thumb it again and head to the rope, start my ascent, nice and slow, all is good, hit my safety stop with another group of divers, the computer is counting down the three minutes for me, all is well.
Get on the boat with a smile, it was stressfull, more stressfull than I wanted, I never felt scared or in danger, I knew what was going on with my air, I knew what was going on with insta buds air, but he didn't understand how much I had, I was OK, but my partner wasn't to happy at the end of the dive, and the dive master took a little ribbing from the other dive master as when I got on the boat I only had 550psi left, he thought it was 55bar.
I'm going to the pool this week, I had a little harder time than I wanted reading my computer, and my time, and finding the inflator, and the deflator. I'm gonna go and get my trim/buoyancy hammered out as my bottom wants to sink constantly wich has me kicking up silt everywhere. Then I'm going to float, look at my gauge, put it back, look at it, put it back, look at it. Then I'm gonna go up 3 feet, use the butt dump, inflate, use the butt dump, inflate ect; ect; You get the point.
I say all that to say " I agree, don't under estimate task loading "