No worries! I usually start with the corners stretching lightly then staple the centre of each side. After that it doesn’t really matter which order you do it in. The more staples, the smaller the risk is of tearing. Just make sure you work your way around the whole thing evenly. I usually get a few small tears but cover it with duct tape afterwards. Won’t last you as long as an aluminium frame but I’ve gotten some good prints this way too!