First thing is to call your contractor to see what he can do. New plaster needs to be brushed twice a day for at least 2 weeks and hand vacuumed with a brush roller. It's also important to keep your PH level in check since the first few weeks of a new plaster are very important to the lifelong look of the plaster. PH will rise due to the curing of the plaster{up to a year} so you will likely be adding acid daily or a few times a week to keep it in check. Learn about pool chemistry and get a good comprehensive test kit (like Taylor K-2006). Do not use a wire brush or an automatic cleaner with feet (for at least a month) since these can cause divots or tracks in the new plaster. If you have a colored plaster it is more prone to mottling or streaking than white plaster (some mottling is inevitable with all plaster). Good luck