Do the bearings immediately. Riding an old, left to sit bicycle, without renewing the lubricant is a mistake. Often times, and I do mean often, the grease in the bottom bracket, head set and wheel hubs has lost its ability to lubricate. I have even seen grease that has turned to rust dust, believe it or not.
What to look for - no grease extruded near the spindle opening is not good. Rough feel with chain off while slowly rotating the cranks, or being able to wiggle the cranks because the bottom bracket is improperly adjusted.
The point is, no-one knows what is in there until you open, clean, look and then do what needs doing to make things right.
Hope that is a help. For a bit more help, have a look at
How To Rebuild A Bottom Bracket.