Best time to hit the mamak so the food is actually fresh?

The secret isn't just timing, it's picking a busy mamak. A packed stall means high turnover so nothing sits around long. My regular spot in Gombak, I go during peak because fast turnover = fresh. For roti, morning is unbeatable, the dough has rested overnight and cooks up fluffy. Also, build a rapport with the abang, once they know you as a regular they'll tell you honestly 'ni lama sikit, tunggu fresh punya'. Ordering fried stuff, ask for it made fresh, most mamak will do it if you request nicely. Avoid grabbing pre-cooked lauk that's been sitting since lunch if you go at odd hours, that's usually the reheated culprit.

Mamak veteran here. Fresh roti canai is basically guaranteed in the morning breakfast rush (7-9am) because the dough is fresh and the tosser is going non-stop. Late night after 11pm is also good because they make fresh batches for the supper crowd. Avoid the dead hours like 3-4pm, that's when you get the sad reheated stuff. For mee/nasi goreng, always order it 'goreng basah' or just watch which wok is firing, if the goreng station is busy it's fresh. Pro tip: order roti kosong and ask for it 'garing' (crispy), forces them to make it fresh on the spot rather than giving you a pre-made one sitting under the light.