I did write it few times but i can't find it now.. anyhow.

If your players came on 1/01/20016 next wave normally be on 08/01/16, that's exactlly 7 days..
If you keep playing new version untill 07/01/2016 and then switch on old version for day or two, you delay the recommended players untill you don't login new topeleven version again.. for example, you want your players on 12/01/2016 (that's my birthday hahah)... you simply use old version untill 11th and then login new version on 12th, new players will be available instantlly.
I know this requires a PC and would make you lose your Bonus but i aplay this on the end of every season and it works perfectlly.

About how to choose the eact position you want:
The engine gives you a player that your team needs, it's doing the math of average quality for every position.
Let's say you've got:
2x GK in your team : one has 50Quality and 2nd one has 30 = Average of 40Q
4xDC with 50Q/50Q/50Q/30Q = Average of 45Q.
3xMC with 55Q/50Q/45Q = Average of 50Q
3x ST with 55Q 55Q 40Q = Average of 50Q.

The engine did calculate that your weakest side is GK with 40Q and will automaticlly give you a goal keeper.

The higher your average lowest average quality for a single position, the higher price on the recommanded players you'll get.

In my case, i've usually got 2x ST with high Quality and 2x ST with low quality. i usually get Strikers as recommended players every season but that's simply because i never sold my 2x ST with 1Star quality.