When should I start preparing my defence?

NOW!!!!! The sooner you start this the better. As soon as you know there is an accusation against you. Make a time line of your history with the party accusing you. Secure by means of download and screenshots anything that may assist your defence. Do not delete anything from your devices doing so, if your phones end up been seized may look suspicious. Keep any evidence you gather in a safe place. We do advise with a trusted person in a different residence. Alternatively in cloud storage is good. You can turn the sign in credentials over to your solicitor. You could also email a copy to yourself. Simply put keep the evidence safe as you may come to depend on it.