You should not assume that your readers will recognise abbreviations and acronyms, just because you know what they mean.
The first occurrence of an abbreviation or acronym should be written out in full without full stops, irrespective of the length of the document.
If it occurs only once in the document, it can be helpful to write it in full and as an abbreviation or acronym.
Firstly, you can assume that some audiences will already know certain abbreviations:
Secondly, acronyms (words formed from the initial letters of other words) or a name of a company, can be written first, with the full name given in brackets afterwards. The acronym is then used for the rest of the document.
For example:
If you are interested in improving your academic listening skills, EASE (Essential Academic Skills in English), may be able to help. You can also get information which will help you work out accurate costs from the international offices of universities and colleges, UKCISA (UK Council for International Student Affairs) and the British Council.