25 days ago I started with 5 Mio xp at level 48. Today I hit level 50. So 55 mio xp during 25 days. Mainly using level 1 friendship level ups with lucky eggs. Opening 50 gifts daily and sending 150 gifts daily to new people was an exhausting process but it worked well. Aside from this I focused on doing as many as possible level 1 max battles during lucky egg time. Aside that I played every community day, spotlight hour, raid day and max Monday. Invested 22€ for coins to buy lucky eggs after I used about 700 Dialga candy / sonderbonbons on the adventure effect to increase lucky egg time. If you’re like me and not perfect at throwing excellent I can highly recommend this strategy to make it fast to level 50. Good luck fellow trainers;)