I'm pretty sure the best way is just to jump straight into Finnish, no point of getting confused by other languages or even toy languages.
If you don't speak any other language than English (your website says you're Scottish) there's some positives in that also as you will have a strong place in your brain for Finnish as that "other language" and you won't freeze so easily when you must speak it. What I'm trying to say is that I at least find myself very often "frozen" when having a conversation in a language in which my level is similar to another language. Polish and Spanish are both languages that I'm able to survive with but if I'm looking for the word e.g. for "Saturday" in Polish I might suddenly find myself stuck in the Spanish word for it. Add Swedish to the confusion and I might as well give up and hope to be understood in English, which is also not my first language, but at least I have a much more strong grasp of it than other languages (except Finnish) so that it isn't subject to the confusion most of the time. YMMV but I hope you get the point and maybe even find some encouragement in it to just start learning Finnish straight away.
Also, since you are Scottish you might already be able to roll your R's and pronounce the letters "ä" and "ö" the "Finnish way" since at least some Scottish accents have those "sounds", which is not the case for e.g. Australian, North American or Southern English accents.
Let me know if you want a Finn to talk to and I'll shoot you an email. ;)
It's weird to see so many words that I already "know" from the Tokipona language just because I'm Finnish and lived a few years in Poland. The words in Tokipona have of course a "wider scope" in their meaning, but here's a few I spotted scrolling through a Tokipona dictionary [1]:
"Kala" is a fish both in Finnish and Tokipona, "nena" is a nose in Tokipona which is "nenä" in Finnish, "sina" (you) is "sinä" in Finnish, "nimi" (name) is the same in both languages, "noka" (leg) is "noga" in Polish, "ona" (she) is the same in Polish. There's more that I'm easily able to remember like "linja" (line in Finnish) which has a similar meaning in Tokipona, not to mention numbers like "wan" and "tu" and words like "mama" (mom) and "mani" (money) etc.
If you don't speak any other language than English (your website says you're Scottish) there's some positives in that also as you will have a strong place in your brain for Finnish as that "other language" and you won't freeze so easily when you must speak it. What I'm trying to say is that I at least find myself very often "frozen" when having a conversation in a language in which my level is similar to another language. Polish and Spanish are both languages that I'm able to survive with but if I'm looking for the word e.g. for "Saturday" in Polish I might suddenly find myself stuck in the Spanish word for it. Add Swedish to the confusion and I might as well give up and hope to be understood in English, which is also not my first language, but at least I have a much more strong grasp of it than other languages (except Finnish) so that it isn't subject to the confusion most of the time. YMMV but I hope you get the point and maybe even find some encouragement in it to just start learning Finnish straight away.
Also, since you are Scottish you might already be able to roll your R's and pronounce the letters "ä" and "ö" the "Finnish way" since at least some Scottish accents have those "sounds", which is not the case for e.g. Australian, North American or Southern English accents.
Let me know if you want a Finn to talk to and I'll shoot you an email. ;)