Below is the structure we've used since 2012.
NLHE Ante Tournament
20-minute ante rounds (L1-L3), 15-minutes thereafter
T10000 starting stacks (12xT25, 12xT100, 5xT500, 6xT1000)
35% average ante increase, estimated 4.0 hours play (12 players)
=================
rd ante bring-in
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R1 50 25
R2 75 25
R3 100 25
5 minute break
R4 125 50
R5 150 50
R6 200 50
R7 250 50
remove T25 chips
>end of optional re-buys<
R8 300 100
R9 400 100
R10 600 100
R11 800 100
remove T100 chips
R12 1000 500
R13 1500 500
R14 2000 500
R15 3000 500
>est. EOT (40 antes)<
remove T500 chips
R16 4000 1000
R17 6000 1000
R18 8000 1000
R19 12000 1000
remove T1000 chips
R20 15000 5000
R21 20000 5000
R22 30000 5000
R23 40000 5000
=================
All players post the ante prior to the hand, action starts to the left of the dealer with a minimum bring-in bet (UTG player must bring-in or fold, but can optionally bring in for a higher amount up to the size of their stack).
Rarely is the minimum bring-in the correct strategic bet size. At L1 with 8 players, there is already T400 in the pot from antes.... so betting just T25 is pretty small in relation to the pot size. Most opening bets are 1/3 to 3/4 pot size (T125 to T300 in the L1 example).