Are Leaves suppose to be yellowing ?

Hi All,
This is my 1st Auto-Flower grow as I usually do photo's. I have 8 plants / 7 different strains growing. I started the seeds on 12-19-18. So they are at day 40. Should the bottom leaves be turning yellow already ? They are all budding up but buds are still quite small & have a ways to go.
I figure at least another 30 days till anything finishes. Seems to soon for yellowing leaves to me but I'm new to Auto's so wondering if this is normal or if I have a deficiency. Thanks for any input.

 

[blue]

Hi All,
This is my 1st Auto-Flower grow as I usually do photo's. I have 8 plants / 7 different strains growing. I started the seeds on 12-19-18. So they are at day 40. Should the bottom leaves be turning yellow already ? They are all budding up but buds are still quite small & have a ways to go.
I figure at least another 30 days till anything finishes. Seems to soon for yellowing leaves to me but I'm new to Auto's so wondering if this is normal or if I have a deficiency. Thanks for any input.

Here's my last day 40 & day 48 photos ... grow had some issues ... turned out beauty!

day 40ish

day48

 

[Buds Buddy]

OK, Kool !!! Mine only have the very bottom leaves yellowing so I think I'm OK & this is just a normal trait of Auto's. Thanks for the info & pics.

 

[Arthur]

Pics would be helpful, I usually don't see yellowing until I've pulled the veg nutes. Your dates have me confused a little, 12-19 1-19 2-19 40 days seems low, strain and breeder?

 

[Buds Buddy]

I guess I screwed up on the date. Looked at my grow log & I started them 1-19-19 (not 12 - 19). Strains & breeders are : Seed Stockers - Big Bud & BCN Critical XXL, Dutch Passion - Critical Orange Punch & Auto Extreme, Sensible Seeds - Girl Scout Cookies, 2 - Fast Buds - Gorilla Glue & Heavy Weight - Wipeout Express. 7 out of 8 are flowering nicely. Big Bud is not flowering yet.
As far as nutes go ... I just started giving 4 plants nutes a week ago & the other 4 I'm just giving Molasses Water. Kind of doing a test to see what happens (the difference in plant growth) between using nutes & just using Molasses. I start my seeds in 3 gallon pots with an empty T.P. roll in the center of it. The T.P. roll is filled with straight Bio Bizz & the outer soil is a 50-50 mix of Bio Bizz & Fox Farms Ocean Forrest.
My nutes are all GH line up : Flora Micro - Grow - Bloom, Armor Si, Floralicious Plus, Flora Blend, Cali Magic, Rapid Start, Diamond Nectar & Flora Nectar. Later I use liquid Kool Bloom.
So far 6 out of 8 are over 3' tall & budding up nicely. The 2 smaller plants are the Big Bud (the one not flowering & the other is BCN Critical XXL). The Critical XXL is about 2' tall & has more bud growth than all the rest & it's the smallest of all 8 plants.
Going to start 6 more today only next time I'll be using Bud Candy & / or Overdrive in my nute regime. Experimenting a little to see if any of these things produce bigger buds. The most I've ever gotten off 1 plant is about 3.5 - 4 oz (photo's). I keep seeing people pull a hell of a lot more off a plant & I want to figure out how the hell they're doing it. I've only had 5 grows so far in the 1.5 years I've been growing (this is the 5th) & the other 4 grows were photo's.
I have 3 complete tent set ups 2'x 4'x 6' that I start seeds in. 4' x 4' x 6' tent is not set up at the moment as I was going to use it for clones & a mother plant for photo's. 4' x 8' x 7' tent that I veg & flower in. I use Intake & Exhaust Fans & Filters + 3 clip on fans. I use 2 - 600 watt Meizhi LED's, 1 Vanq 4 light Cob, 2 - Kessil Lighting Magenta Cobs & 8 LED Red/Blue Spot lights for side lighting & I use a humidifier. Temps stay 75 F lights off & have gotten as high as 84 F lights on. RH stays between 30% - 45%. I know the temps & humidity aren't perfect but it's not real bad either & the best I've been able to get it without adding A/C to the tent.
There you have it ... my grow & set up.
I should say this is my 2nd attempt at Auto's. I tried Auto Beasts "How to grow a perfect auto from start to finish" & it was a total failure. All 3 plants died shortly after sprouting. So I decided to try my own way & it seems to be working quite well. Not sure if Auto Beast is a grower or a salesman for Bio Bizz the way he raved about that soil. It's not all that great. It's good for starting the seeds; but that's about it.
Oh well, time to water. 36 oz. per plant everyday @ 6.3 pH. I may have to up the watering soon as they're drinking up the water daily.