Simplified regime for freelancer moving to Portugal?

I'm planing to relocate to Portugal as a freelancer in a couple of months but I'm struggling to find correct informations regarding the simplified regime.

I've been looking for a accountant dedicated to freelancers in order to answer my questions but all I could find was huge firm with super expensive fees probably tailored for huge companies. If any of you had a link for such service that'd be great!

Alternatively if any of you have the answer to these questions that'd be wonderful:

Under the simplified regime, is that true that you get 50% tax exemption the first year and 25% the second year? If so, does it work by calendar year or on a rolling 12 months basis (so should I wait until January to register)?

Also I've read that you're exempt from social security contribution on your first year. Is that correct?

Many thanks to all the people that could give me some answers.