Unable to set reminders relative to the event
I'd like to be able to set reminders relative to the event however the syntax "6 months before deadline" doesn't appear to work.
Example: my passport expires August 2016, I'd like Todoist to remind me 6 months before. I suspect the way to do this is to create a task "Start process of renewing passport" with a due date of February 2016?
there are 2 types of reminders - relative and absolute. A relative reminder can only be set if the task itself has a specific due time such as "tomorrow at 16:00". In such case you can set a reminder type "relative" to a certain time before the deadline specified in the task. However, the longest period for such reminder is 1 week.
In your case, I would advise to use absolute reminders. Such reminders can be set to any date and/or time even recurring dates as long as their format is accepted by Todoist. "6 months before deadline" is not a valid date format so I'd advise to set a task due 1. Aug 2016 which would be the deadline to renew your passport and the reminder could be simply set to "1. Feb 2016".
Note - you can even set multiple reminders for the same task, so you could add reminders for each month to make sure you won't miss the first one - all in this one task.