I had 8 steps replaced last year, the old limestone type, with new concrete and it was about $2600 by Andreas. I also had to have some brick work done as well as the steps were place under the bicks and started to come out when they broke the old limestone ones up. Not sure what you have exactly, but you may want to budget about $3000 just in case. As for doing it now, it can be done if everything is covered or tented over, but that will also add more $$$ to the work. Best to wait until early srping, mid March or certainly April.