That is the start! For the future jams you will know when and what slowed you down!
People already told about steps being a bit too small... But other than that - always try to make small level. Do all the mechanics you need to do on it first. Make health. One enemy. One attack. Death and Win condition. All that mandatory stuff that is in the rules. And then start working on the level :) That way even if you won't make stuff in time - at least you will do 'minimum' so you will be able to get better reviews and more experience with that.
Never give up and keep going!