This tutorial offers step-by-step instructions representing one way to input the score. Only the part before "Allegretto" will be inputted. The full first movement is included in the PDF file, so you can input it yourself.
12.6.4.1. Start with the Easy Part
The best way to get started on large scores is to just start with something easy. Nothing can be easier than doing nothing, so let's first input the multi-measure rests in the wind sections and timpani.
Count the number of measures of rests. In this case, all of the winds and the timpani have thirteen or more measures of rests before their first entrance.
Let's put in those thirteen measures first.
In the NOTES section, find the flute section, and put in R2.*13 |.
The R symbol means "full-bar rest" (or "full-measure rest"). LilyPond draws full-bar rests differently than rests than rests that simply take up the length of a whole bar.
Copy and past that into the rest of the winds and the timpani.
The timpani and trumpet/clarini parts have six further full measures of rest, before the measure with a fermata. The fermata can't be included in the multi-measure rest, so we'll treat it separately. Add R2.*6 | to the timpani and trumpets parts.
The horns, bassoons, and second oboe have one further measure of rests, so add R2. | to those parts. Full-measure rests should always have a capital letter R. This tells LilyPond to properly center the rest in the bar.
