once the plant shows pistils ?????!

once pistils have emerged does this mean the plant is definetly goimg to start flowering ??

If so how long does it take to see the bud growing after pistils have emerged ?

Since pistils have been on my plant for nearly 2 weeks, there is pre flowers but no visible bud

Pistils/pre flowers simply mean that the plant is female and sexually mature and is ready to start flowering. Unless it's an auto, then it will start flowering.

I have plants in this state for over 3 years (mother plants). They don't flower until a 12/12 light schedule is introduced.

They're ready, up to you to figure out how to play it.

Wet

The bud will begin to form, don't worry. When I switch to 12/12 I wait on average about 10 days or more before pistils begin to really show, and that's when you should also begin your flowering time countdown so you can at least have a somewhat accurate time table of your flower time. Many begin counting right at 12/12 whether there are pistils or not, and this will mostly lead to an early harvest estimation. Of course you want to look at the trichomes under a scope for harvest as well as the flower time.
You'll notice the growth of the buds with each passing day. It is amazing what a seed can create. You are just getting impatient and excited and that's normal.

Thanks man, the only thing is they are outdoors so i cant flip the time periods iv got over 80 auto's and they are all showing pistills n preflowers, just wanted 2 know when im going to see some buds