it's chicken and egg story. once i see him having sign of tiredness, i'll try to make him sleep, but if he doesn't sleep within 15 mins, i shall stop trying. then later he'll b very tired, and it'll b harder to make him sleep. it's really tough...
ok, i shouldn't worry too much about establishing a nap schedule, which i really don't think i can do that at this moment.

now another problem emerged. when i first wrote this thread, i was able to carry him to sleep and normally able to tell when he's tired. but suddenly a week ago, he cries so hard when i carry him with the normal way (horizontally with his head on the crook of my arm). and i need to carry him over my shoulder, he might slowly drift off to sleep, but it takes very very long time with some fuss. this has great impact on my back. out of suddenly i couldn't gauge whether he's sleepy. when he first yawns, rubs eyes, pulls ear...all these are not enough to indicate that he's really tired as he just won't sleep.