Need sound advice (seedlings)

A guy had started some seedlings using sunlight. After a 1.5 weeks the weather became cool, cloudy, and rainy. So he was wondering if he switched them to artificial indoor light for a couple of weeks before putting them out to pasture how long could he run the light cycle without causing problems once he returns to natural light in a couple of weeks. Point being he wants to get as much bang for his indoor buck as possible in the coming 2 weeks. I was thinking he could do maybe 15-18 hrs. of artificial for the next couple of weeks before putting them back out under the sun for good? Much appreciated if anyone would take the time to offer up sound advice. Thank you in advance!

go for it wont be a problem . yes it the plant is seeing what 15 or more hours of light out side depending where you live . give them 18/6 until its warmer and replace out side . wont be a issue . try to put them out in the early morning . when you replace them so they get that extra time to get adjusted . no worries. when they are in veg its takes a lot to stress them .

Thank you very much for the timely response Mr.Diesel! Your advice puts his mind at ease. Ol boy hasn't did any gardening since 2005 and has never used any artificial light at any stage of the grow so he is understandably hesitant. Thanks again

you can just place somthing over the plants or move them to another place wich is rain safe. though if they are only 1.5 weeks old, rain is no problem so yo dont have to move them at all. plus' if you're gonna take them in for 2 weeks' you should think about the length of the day hours where you live. if you give them electric light for 18 hours and then move them to 13-14 hours of sunlight they coud start flowering sooner then you want, so you'll get weak plants and maybe low yield. if it was me i would just leave them where they are, or protect them with transparent plastic at max. they are young and in veg, must be around 2.5" tall,cloudy is fine.
peace

I think they should be fine. I'm in the same boat.. half of my ladies are already outdoors and the other half are still inside vegging. The ones that I just transplanted the other day ( A day before severe thunderstorms that lasted a day and a half) have grown significantly. From what I've read, even on a cloudy day the sun is still more powerful than any artificial lighting.

I like how you say "his", when you really mean yourself.