If he is that young and weighs 74g, you should be feeding every 3-5 days. 7 days is kind of a stretch if you ask me, that is more when they are like 500g or so. And if he is 74g, then you should be feeding him rats/mice that are 8-11g. Also if you know his weight, does this mean you got a scale? If so, again just weigh the prey when you get home. Eyeball by his thickness the first time, then when you get the prey home, weigh it and then adjust next time as needed. Feeding a little larger prey once or twice wont hurt him. I've fed Dot stuff that was clearly too big but for some reason I didn't catch it and she ate it and afterwards it looked like she ate a football. She then went into a food coma and barely slithered into her warm hide. Two days later she was out and about looking for food again. So like I said, a little too big once in a while is fine, just don't make a habit of it.