I agree with MatildaR.
Tomorrow I'll be replying with abbreviations as titles can be cumbersome to continuously write.
When you introduce your texts in the introduction, do it then - the 'declaring'. Markers will know that hereafter you will refer to the text 'titles' as these abbreviations. =)
Of course, in saying that, not everything can be abbreviated. Try to abbreviate as little as possible. Instead of abbreviating to save time, expend more effort on being concise - in other words, cut out sentences that you really don't need.