1. what would be considered proper watering A. complete saturation of the soil with some run off, then waiting a few days for it to dry out. B. Feeding a little at a time 2 to 3 times a day. 2. Could you turn a month old vegging plant (18-6) to 12-12 until sex shows and switch back to 18-6 without shocking the plants too bad. The plants have at least 4 nodes each with decent branch formation.
When watering you basically want to insure that there are no dry pockets deep within the soil, usually that involves saturating the soil but make sure not to drown the damn thing, but with proper drainage you should be alright. A good method to avoid dry pockets in your soil is by watering slow or in two stages. If you simply dump a lot of water in your soil, most of it will run to waste without being absorbed. I like using drip irrigation. Not only is the water delivered in a slow steady amount, I can water in two stages. You want to make sure the soil dries up in between watering. Not to the point where root damage takes place or where your plant starts to wilt. If the roots stay too wet you could develop root rot and a host of other problems. Before feeding the plant however, be sure to first use plain water without nutes and then your nutrient enriched water. This is to prevent the roots from being shocked with nute enriched water.
You shouldnt be watering everyday... You want to let the soil dryout a bit so that the roots get the O2 that they need. Water your plant till about 25% of the water you put in drains out of your pot, I like to give it half the water then wait 15 minutes and give it the rest ( so you dont get dry areas of soil) You dont want to water again untill the top 2" of soil are dry and your pot feels light. You can switch a plant to 12/12 to sex and back to veg but going to loose a few weeks in the switch, and then have to switch back again when you want to flower. I'd just wait another 2weeks in veg and then switch to 12/12 and not waste the time, you will probably see preflowers by then.
^Yep, water thoroughly when you do water then allow to dry out in between. Watering a little bit several times a day will suffocate the roots. You can flip to 12/12 to sex and then back to veg, but true that will slow you down. You can take clones of the plants and flower those to see sex while you let the main plants continue vegging. Or you can just wait, sometimes they will show sex before you switch lighting.