You can head into PvP whenever you like, the experience is not totally dissimilar sometimes. The biggest change will be that human players will punish you for mistakes which the AI won't - with the threat of getting ganked increased, just remember to play more conservatively at first.
Most importantly, communicate with your team before the match begins and at the very beginning of the game. Ask them which lane you should go, and tell them that you haven't been playing PvP very long.
You're less likely to get flamed later on for any perceived 'mistakes' that people think you've committed; even players who do like to whine and blame others will appreciate it if you lay your cards down at the beginning of the game. This will help you avoid situations where you head over to the middle lane and some other champ runs up behind you saying 'FFS noob go to bot omg' and starts pinging the minimap.
Try to practise with wards and such, but try not to overcomplicate things. When I first started playing LoL I watched lots of videos and streams, learning all the pro tricks and strategies, and by the time I played my first PvP game I was so focused on wards and baiting and calling MIA and buffs etc. that I became unco-ordinated and distracted.
Just farm your lane, focus on last hits, and don't be too aggressive looking for a kill - trust me, at low ELOs especially, your main cause of death won't be from enemies making a co-ordinated and brilliant play, but from enemies who were given an easy kill because you over-extended yourself or made some kind of mistake.
Shrug it off and continue playing and play a Champion who provides abilities which are easy to use and be effective with - there may be nuances and skill involved when getting off the perfect stun with Taric, for example, but at the end of the day if you heal your lane partner and stun an enemy champion when you can then you can't go far wrong!