Code: C
static int iStart = 0;
static int iPad = 0;
char title[] = "abcdefghijklmnopqrstuvwxyz";
int titleLength = strlen(title), overChars;
char titleToShow[20];

if(titleLength > 20)
{
    for(int i=iStart;i<20+iStart;i++)
        titleToShow[i] = title[i];
    iStart++;
    titleToShow[i] = '\0';

}
else
{
    // Before padding with spaces
    for(int i=0;i<iPad;i++)
        titleToShow[i] = ' ';
    // Copying the characters
    for(;i<titleLength;i++)
        titleToShow[i] = title[i];
    // After padding with spaces
    for(;i<20;i++)
        titleToShow[i] = ' ';
}
Just this is the handler to the timer where you pad based on the static variable.