Hi there, hope you are enjoying BYC!
At the stated age.. to those with a bit of experience.. there is no guessing.YES, your suspicion is accurate and that is indeed a cockerel.
Please note that there are many comb types and while the size is one indicator.. color is also key, notice the wattle size and color as well. Then look at leg thickness.. these are all clues to consider... in addition to behavior.
Pointy saddle feathers will start coming on most breeds around 12 weeks of age.
Are ya gonna be able to keep him?
Consider adding your general location to your profile as it can help folks make their best suggestions possible at a glance.. say if you do end up needing to re-home (get medical supplies, feed, etc) or anything like that.