Each SEO project has different timeframes.
Under-optimised pages requiring technical improvements may need only a few days to see changes in the rankings, but the process of auditing and optimising the page may take longer.
For pages with a penalty or needing off-site SEO and link building, the change may take longer, especially in competitive spaces.
Initial SEO results might start being visible after a few weeks in those pages and keywords that weren’t optimised, with bigger changes to the link profile and ranking of more competitive sites may be seen in 2 or 3 months time.
For more information, ask us about your particular case.