Either way is safe when done right, I have done both! If you strip her, you just don't want to keep her out of the water too long obviously, and when you put her back in the water for a moment, let her swim a bit and get to breathing. I keep my hand in her tank for a minute to let her get calm and pick her up, she fights me the first 2-3 times I take her out, but then she tends to be a good girl after that.
but ok
let's get started.
I have had 3 batches of fry from my yellow lab, and she continues to get prego usually 2-3 weeks after I put her back in to swim the the rest.
First time lab mothers usually spit a low number of fry, sometimes as low as 3. My lab spit 9 her first time, which is fairly good!
I recommend a breeder box, and put her in after 1 week or as soon as you see her getting picked on by her tank mates. Stress will cause her to eat the eggs or spit them early (and you will lose them)
They say labs carry around 21 days, but mine tends to be around 29. Her first time, she ran to 27 days. 2nd time, 29 days. I stripped her just yesterday at 21 days due to me needing the breeder box for another, and they still had the 'egg yoke' on them, which could potentially go sour very quick. However, they are doing fine as of now.
If you are home all the time, and tend to keep a good eye on your fish, then I recommend letting her spit em. She's a mother, and let her do her motherly thing! Now, if she's pushing past 25 days, then I would potentially try to strip her, which is fairly easy to do. YouTube has quite the many videos on it, just watch more than 1 so you know different techniques. However, like I said, let her be a mom at least once! The reason you need to keep an eye on her though, is she can eat her fry just hours after spitting them out. She will not have eaten for around 20+ days. Labs are supposedly good mothers and keep them safe for awhile, but I never trust it. So separate them as soon as she has spitten them all out.
Once mine spit/are stripped, I move them to another tank I have so they remain safe. DO NOT put them back in your main tank, as the other fish will eat them do to population control, any even hunger
Oh, and a last note. I strip the fry into a separate bowl/container so I can put mom back in the breeder box to breath again, until I strip more fry from her. If you try to strip, once 1 or 2 come out, look for a fat/bloated belly. That is the egg yoke, and they aren't completely ready to be out of the mommas mouth. If you put the fry back in the breeder box with mum, she will usually suck them back up and continue to cook em for awhile
Good luck, and your going to enjoy it. It's a miracle, just like seeing other babies in the wild, at least this one isn't gross when it comes out