I think it works better that way. In a few of my videos I ask in the beginning but mostly I wait to the end. the problem about that (obviously) is that people might not watch your video till the end but if the actually do I think you have a better chance of getting a new subscriber
Yes HiEnergy, I have mixed feelings. But I do think there are some who ask for subs in a considerate way and are not overly pushy.I rarely ask people to subscribe in my videos, merely in the description.
I put a phrase like "Subscribe and use the bell feature for getting informed of upcoming similar videos." near the end of the description.
I hate videos where the creator asks me to comment and like their video, subscribe the channel, use the bell feature, visit their fb, hug their cat, do whatever... best thrice in a row. Those regularly get a "thumbs down" and a comment stating the reason for the dislike.