If you want to visit all Canary Islands you need to start at Lanzarote and slowly travel towards El Hierro. From there you can fly back to Lanzarote or other destinations. If you want to complete it 100% don't forget the day trip from Fuerteventura to Lobos. And from Lanzarote  to La Graciosa. You need at least 2 weeks of total time to visit all the islands, however, 3 weeks is much better, since this would take the ‘hurry and stress' away from the trip. Especially take your time in Los Cristianos to make all connections work in a really good way. Important to know: You'll be spending at least 20 hours on ferries! And it will cost at least € 800,- by just the ferry costs.