for me, most everything sprouts within the first 72 hours(paper towels). before the tails get to long i put them in 20oz cups. almost nothing has ever cracked open after 4 days, everything that doesn't gets put in a cup. the one that took a month was johnny blaze from legend seeds, nevills haze x blueberry, bought them in 2006 and just started them this year. they are 'old' genetics so its perfectly reasonable that its just a 'slow starter'.
give it a few days, your enthusiasm is the building blocks of an awesome grower.
but some of the stubborn seeds can take a lil bit.
the fact that you're meticulous about ph etc tells me you are alright and its nothing you're doing.
keep in mind, burgeoning medical markets in the USA has changed the seed market a bit,
so non-viable seeds are a little bit more readily occurring than they have been in the past, however in a moist but not-waterlogged environment, your seeds should spout based on what you've already done.
wait it out a couple more days, if that doesn't work, try some moist paper towel layers that you've rung out for excess moisture and give them a lil bit more time
I germinate the seeds directly in organic pro mix. Plant, water and then leave in a warm, dark place. Suppose it depends on the strain and viability of the seeds. Mine normally pop up after 7 days, but take longer when the weather is cold. If nothings sprouted after 4 weeks, normally plant another seed - but I've had late sprouters.