seo – 150 ‘no-follow’ links to another site I own. Will I get a penalty?

I have two websites. One website has 50 articles published and is doing quite well. In all the articles published, I have 2-3 links that go to a subdomain of that website. Now I just started a second fresh/new site, and I would like to replace all the links in the current articles on website 1, to website 2 (so not the subdomain, but the new/fresh site).

Question:

Is it okay to do this without getting a penalty? Just to be sure I am making all the links no-follow. Can I replace these 150’ish links all in one day, or should it be spread out over several days? Im quite new to this ‘technical SEO’.

Thanks.