Unfortunately you cannot schedule a post from within the Linkedin platform itself (at the time of writing)! In the mean-time, here are 3 third-party platforms with which you CAN schedule posts to Linkedin;
Hubspot – Mktn Hub Pro Acc frm £655 p/m 😳Hootsuite – Pro Acc frm £25 p/m 🙄SlackSocial – FREE 🙏