SEO specialists are not magicians, and search engines today do not give "work wonders". Therefore, it is a good idea not to spend money immediately, and read the information on the Internet and evaluate your site yourself. Some sites such a promotion simply can not help.

It is definitely necessary. As early as possible. Now a SEO specialist is involved in the development phase of the site. But now you need to contact and order a site audit. Then you will discuss whether to promote the site at all (because often due to the competitiveness of the niche is simply impractical to do, and there are other reasons enough). Promotion strategy, which technical errors should be corrected, etc. I am working now with SEO company "To-The-TOP!" and already see the first results. But there is still a lot of work ahead.