It probably won't go on sale for a while, and when it does it'll probably be the normal $10 50% off not the special $5 75% off.
If $10 / £7 is that much to you, wait. As I sincerely doubt that I'd recommend you not wait and purchase it soon. The new player inexperience will be wearing off in the next few weeks, and soon it will go back to having mostly decent SLs.
If you wait until a sale you will have to deal with most everyone else being new too; it's really not the best way to learn the game.
P.S. If you do buy the game, only go rifleman until level 20 honor. Don't worry about the other classes and their guns - they have very specific purposes that you will learn watching as rifleman. You will be highly tempted to pick those classes after picking up their guns off the ground - and you will do better with them - but that doesn't mean you do well as that class, and better doesn't mean good.
Get used to the boltaction and you'll dominate the game in no time flat - you'll even develop a preference for one or the other (I prefer the 91/30). Enable manual bolting and native languages, disable automatic reload, and remap RMB to hold (not toggle, as is default).
left ctrl for use (pick up gun)
left alt for prone
C for crouch / stand (toggle)
R for reload, hold to check magazine
V for voice macros
mmb for melee / alt fire
Z for spotting - please spot the enemy tank if you see it!
capslock, O, P respectively for team, global, and squad voice chat
Y, U, I respectively for team, global, and squad text chat
M for the full map, mouse wheel to zoom - remember to check the map for friendlies before throwing a grenade blind!
comma, period, semicolon respectively for change team, change class, and change spawn point
If you use ShadowPlay, I recommend native resolution, 5 minutes, 30fps, and F11 as the shadowplay save key. If you're not using fullscreen you will need to enable Allow Desktop Capture. If you're using fraps/obs/whatever you'll already know you'll lose frames, and if you're using dxtory you probably know what you're doing.