The split will happen when the official blockchain will be live, meaning it won't be conducted on the Omni platform.
With regards to the bonus- up to a 15% bonus will be distributed to Agoras holders who didn't move their tokens after August 1, 2017. There are two options:
If your tokens have been locked (there are ~12 million locked tokens), you have already received the 15% discount, as appears on your personal address.
If you decided not to lock your tokens, you will get up to 15%, depending on the time in which you didn't move your tokens (by using a formula to calculate the effective rate of your bonus). For example, assuming you moved your tokens after 2 months and the holding period* was 20 months, you will get an effective bonus of 1.4074%, according to the following formula: (1+15%)^(2/20)-1 = 1.4074%
*holding period = time from August 1, 2017 to the bonus distribution