The beginning is extremely basic, but not everyone knows.
- Wraiths, Wolves, and Mini Golems spawn at 2:05 and respawn a minute after the mob is cleared.
- Buffs (Red and Blue) spawn at 1:55 and respawn 5 minutes after the mob is cleared.
- Dragon spawns at 2:30 and respawns 6 minutes after the dragon is killed.
- Baron spawns at 15:00 and respawns 7 minutes after he is killed.
What this translates to:
Junglers who start at red buff (Shaco, Lee Sin, and anyone else who might want to early gank) will have their Red buff respawn at about 7:10, junglers who start at blue buff (almost every other jungle) will have their Blue buff respawn at about 7:10.
What that translates to for mid lane:
If you see their mid lane walk from blue side after leashing, you can expect their blue to spawn at ~7:10. What that means is that at about 7:20 you can expect your lane to start walking over to their blue buff.
This is important because if you time it correctly and have health and mana before that time and your jungler comes with you you can potentially disrupt or steal the blue or even get a kill on the midlane or jungler. However, this is only if your jungler comes with, their jungler is donating blue buff to mid lane, and you and your jungle have the power to commit to a kill (some junglers are weaker than others, such as Sejuani vs Lee Sin, Sejuani being the weaker).
You can expect the buff that the jungle did not start at to spawn at ~9 minutes. This is important to note because if you are blue side you can expect that their jungle will not gank bot at around this time. Alternatively, if you are purple side you can expect that the jungle will come down after red buff if your lane is pushed. However, on both sides it is viable to gank mid.
What this translates to: ~9 minutes is the time that blue side can make a play on bot. This can range from mid and jungle coming down and ganking to force a dragon or turret or just simply forcing a 2v2 fight between the supports and ADs. This is only possible if you are counting summoner spells or have a distinct advantage over the other lane. Don't try to be a hero and force things, it usually ends up poorly for you.
Why is it safe?
It is safe to make a play at these times because you know where their jungler is. If he comes bottom, his red buff is likely to be taken and give one of the lanes a very large advantage. If the gank is unsuccessful, they lost timing of their buff, the buff itself, and the rather large amount of gold that the buff gives. It also gives the jungle that isn't ganking time to counter jungle things like wraiths or wolves, camps that are quite valuable. The only way it would be good to give up your jungle to the enemy is if you pull off a successful gank, so good wards around this time can really bring out great play from even sub par players who "can't think for themselves."
- Blue can be given to mid lane around 7:20 (and it should almost always be donated)
- ~9minutes is a decision making time for junglers and laners, be cautious around here.
- Make your plays when you know where their jungle is.
9/10 times, the players that are counter ganking actually win the fight in my opinion. Though this isn't some statistic, I'm curious what the actual statistic would be of this, and I'm sure it is high in the countergank favor, so don't get counterganked.
Fun fact and pro tip: In your options, turn on timestamps. This will automatically time everything in chat, to include when dragon/baron is killed or when you say "eb" to mark when you took their blue buff. You can also press and hold Z (default) to extend your chat and scroll up to see what the timing was if it goes off screen. This will make timing everything a TON easier. Just do it.