need some tips!

My son is about 5.5 months. We've tried a variety of wake window times and still can't figure out what little man needs. we've tried 1.75/2/2/2. 2/2/2/2, 2.25/2.25/2.5... he seems to just fight it. he will wiggle in my arms for a while then just sleep for 30-45 min. We plan to start sleep training at 6 months and to move him to his own room. I'm just at a loss of what else to try for day time sleep.