It’s been 4 full days since my first beer has been fermenting. I’ve noticed today that the kraeuaen has fallen below the highest line where the kraeusen was. Is it time to start taking hydro measurements? If you tell me I should wait two weeks I will ignore you.
Go ahead! You don’t need to at this point but why not? Be sure to spin your hydrometer to dislodge any air bubbles. Note the measurement. Calculate you abv. Good practice! Then taste it, or course! Enjoy!
I don’t need to, as in it’s too early?
Also, does anyone bother cooling the sample before sampling?
Wait two weeks. 
It’s tempting to want to check gravity early and often, but you’re wasting good beer.
The goal when you check gravity is to determine when the yeast is essentially done fermenting so you can move on to the next step, whether it be lowering the temperature to age it for a while or simply to bottle if it’s a beer style that’s best to drink without aging. There’s no way your beer is close to done at 4 days with krausen still on top. I would at least wait until the krausen drops and the beer clears a little. Then take your first gravity reading. Three days later, take another. If there’s no change, and it’s reasonably close to your expected final gravity, it’s probably done.
Oh, I do sometimes cool the sample when I taste it. I usually first taste it warm, since it’s easier to pick up off flavors when it’s warm. But I sometimes taste it cold to get a better idea of what it will taste like at normal serving temperatures. But at four days, I can just about guarantee you it will taste weird.
I brewed a 1.052 pale ale 4 days ago and pitched wlp008. Activity slowed to a crawl but it still had a thick, meringue-like krausen. A gravity reading showed 1.012 and it tasted great- although it won’t see the inside of a keg for at least another week. Because I sample the grain, the wort, and the beer throughout the brewing, fermentation and conditioning process, I can understand the whole process much better than if I just waited 2 weeks. A 3 ounce sample is not a waste as long as you can learn from it and grow as a brewer.
I agree wait. It’s cool and all to taste at different points in the process but there isnt anything you can do if you dont like that sample anyway. It can be disappointing sometimes if tasted to early just because the flavors are not rounded out per say. It will have a yeasty taste/characteristic with some flavors more prominent that others. It is better to wait just because the more you touch that beer the more chance for nastys to be introduced.
All that said once upon a time ago i just couldnt wait either and tasted at many different stages. Now i wait at least a 7 to 10 days, check the gravity at my calibrated temp for my hydrometer (60F) and taste at that temp. Then i cool it for a few days and rack to keg with force carb x 2 weeks and enjoy. It does get better every week after that. It seems mine peek at around 7weeks. Meaning nice lacy head, carbonation and well rounded flavors.
Well said.
How cool do you drop the temp at the end of fermentation? And secondly, do you cool your sample to 60 for testing?
you don’t really need to cool the sample to 60, the correction tables included with your hydro are plenty accurate for the 5-10 degree difference you are talking about (add about .001 at 70 by the way).
sample it what the heck, it’s your first brew. sample it every day if you want. just sanitize everything that touches the beer in the fermenter.
Is there any need to start to increase the temp of the beer when you near the end of fermentation?
You don’t “need” to unless you’re fermenting really cool, but it definitely helps to speed up the last few days of fermentation.
Im of the school that the less you muck around with it the better. just set it and forget it™ Im sure others disagree. but i make my beer to drink, and i dont enter in comps etc, so i dont expect perfection… Yet:)
+1
It’s the search for perfection that is all the fun, not finding it and guarding the secret