After inoculation of the jars, tighten the lid bands and retape the needle holes. A tight lid preserves the water content of the substrate (very very important) and the growing and spreading mycelium will do fine with a tight lid all the way to the appearance of the primordia (using the air in the jar only). Place the jars in a safe place out of direct sunlight. Indirect light is all that is required. If the temperature is kept around 70 degrees, germination will begin within 3 to 5 days. Germinating spores appear as small white fuzzy spots, quickly growing and spreading with cottony white growth and strandy "rhizomorphs". Any room temperature is O.K. If it gets cold indoors, over head light shinning down on the tops of the jars is a perfect heating technique for this culturing stage. A clamping type light with a reflector works well for this. If this is done, keep the temperature around 70 degrees (don't overheat the jars - monitor the temperature with a thermometer). A warm overall house temperature is fine. But in the overall view, cool temperatures are never a problem. The rule is to not overheat.
There are two choices with the lids during incubation - tight or loose. With a very high moisture content (good for fruiting), a tight lid can cause water to collect in the bottom of the jar. This is to be avoided. Water condensing in droplets on the inside of the jar during incubation is normal and is to be expected. If puddling on the bottom of the jar occurs, the lid should be kept on loose during incubation. Tape the canning jar lid to the band to make the lid act as a one piece lid for raising and lowering.
An excellent way of depuddling the jar is to use a long syringe needle and syringe. Without disturbing the top vermiculite layer, insert the long needle down to the bottom of the jar. Tilt the jar so that the water puddles down to the needle point and suction out the water. This works really great, but one needs an extra long needle to do it. Doing this can facilitate superb fruitings with the high water content without the puddling problems and possible deterioration of the substrate because of the water (drowning). With a high water content, there might be more than one depuddling procedure needed.
Also, there is another and even simpler way to depuddle the jar. One just simply inverts the jar and lets the water run down the side and is absorbed by the dry upper vermiculite layer. Most people do this and report excellent results.
If the substrate is on the dry side, a tight lid will preserve the moisture content. It is all a matter of the balance between the water needs of the mycelium, the size of the jar, the available air space in the jar and the type of vermiculite used. Only by simple experimenting and comparison can the right balance be found for a given set of conditions. Take notes and go with what fruits the best. But after many years of seeing all of this and all over the internet - web - the basic PF substrate formula as given rules.
After the substrate turns white with the mycelium (2 to 4 weeks after inoculation), the jars are left to sit in indirect light. The mycelium will continue to infiltrate the substrate until it gets enough food to trigger the fruiting cycle. In less than a week to a few weeks after surface colonization of the cake (cake appears all white), tiny white "pin" like structures begin to appear. This is called pinning. This is the beginning of the fruiting cycle. Soon after that, within the week, small round fungus growths appear that soon begin to turn yellow.
Lastly, "primordia" start to grow. These are tiny worm like structures with tiny reddish heads. These are the first mushrooms.