Newbie grower, when to flower?

[Errbi]

Hey guys

You could say this is my first grow as I had to get rid of my previous ones when they were really young.
Anyways, I've been vegging for over 1.5 months now and I'm wondering how much they are gonna stretch during flowering.. The strain is Skunk 1# feminized and flowering time is said to be 45-50 days. I'm aiming for a large yield.
16 liter pots in the picture if that helps understanding the current plant size more clearly. My tent is about 2 meters tall. Air flows through a glass tube around the 600W HPS bulb really well so it doesn't produce too much heat below unless really close to it.
Started 20/4 and now I've been 18/6 for over a week as well as switched from MH to HPS to ease off the upcoming transition when I switch into flower.

Any ideas when to flower? I have no idea if there are any downsides to long veg time and aiming for max height my grow space allows.

All replies are appreciated!


Oh, and as you can see one of the plants is a lot taller than the rest.. I recently topped that plant to hopefully reduce the difference a little bit. You can see the new 2 tops growing if you look closely.
Also looking for any other tips to increase yield! top or FIM the rest or are they fine like this?

[M_C]

They'll stretch at least to twice the height when they flower. If that is a problem then now is a good time to chop the tops off them to get them to a more usable height

[Errbi]

at least to twice the height

Do you know if it's likely it will be more than that? I don't want to take a risk that I run out of grow space. Also I heard it's possible to bend them if they are about to get too tall, but I don't know.
I have enough room for the tallest plant to like triple in size right now and that would be about max I have space for.

[Errbi]

Also the strain is 35% sativa 65% indica.
I literally welcome all growing advice as I'm just a newbie