https://www.reddit.com/r/factorio/comments/1gzh1ca/courier_xs_small_fast_lossless_cargo_runner/
This ship will kickstart itself. Import nuclear fuel only. (Time for kickstart highly depends on asteroid productivity. up to 1h on level 0. 5 minutes at level 10)
Building over Nauvis is recommended. More then 13000 SPM throughput 2-way round trips. No cooldown between trips
If your asteroid productivity is low (or non existant) it will reduce fuel production and thus limiting speed. If you research asteroid productivity levels it will increase its speed progressively. Quality collectors can help