For now make use of the forum features like your own signature space, website link, skype and other contact info
that can be edited here: forumProfile (if the link didn't work go to your profile, then click "Forum Profile Information")
Link them to any of your affiliated pages and be active on the forum (do not spam) to promote the links without being annoyingly-obvious.
You can start by establishing Social Media pages, Discord and Telegram groups as a drop point for interested individuals to share your vision, mission and goals while the project rolls on.
Whether they are interested to the bounty, airdrop or potential investors, any person can act as a "free advertiser" for you.
Start the "actual marketing" once you've completed a solid plan, a reliable team and a considerably 'working' part of the roadmap.