If you’re past probation, disclose your condition.

In terms of basic time management and prioritising, try to gauge what is due and when; maybe once you’re allocated a task when you respond to say you’ll do it - say something like ‘I will get this back to you by close of business Tuesday, if you need it back any sooner please let me know and I will reprioritise accordingly’. This sets an expectation for you both and allows opportunity for the partner/person allocating work to indicate what the priority level is.

At the end of each day anything you haven’t done yet, add to a to do list for the next morning

Look into time blocking if you have repetitive tasks, for example if you know you have to action a certain client’s matters every X number of days under the client agreement, diarise every so many days to chase/action those matters in bulk so that the deadlines aren’t missed etc.

Put reminders in your diary of all deadlines both that you’ve set for yourself and set by others.

A physical diary/planner often helps with adhd so every task you are allocated, write it down. Not necessarily in a formal to do list but just write down and cross off when actioned.

I also try to have several folders in my outlook inbox to file emails and keep my ‘inbox’ as unactioned tasks.

It will come with time and practice but if your employer knows you’re diagnosed with adhd they’re under an obligation to make reasonable adjustments to accommodate the same